TABLE 4 ESTIMATES OF 13-MONTH SMOOTH SOLAR ACTIVITY FOR BALANCE OF CYCLE 23 CYCLE 24 AND BEGINNING OF CYCLE 25 TIME SUNSPOT NUMBERS GEOMAGNETIC INDEX (Ap) PERCENTILE PERCENTILE 95.0% 50% 5.0% 95.0% 50% 5.0% 2008.1667 MAR 4.8 3.8 1.9 7.8 7.5 7.0 2008.2500 APR 6.4 4.1 0.6 8.2 7.4 6.7 2008.3333 MAY 9.3 4.5 0.0 8.7 7.5 6.5 2008.4167 JUN 11.3 4.8 0.0 9.1 7.6 6.0 2008.5000 JUL 12.8 5.1 0.0 9.4 7.8 5.8 2008.5833 AUG 14.7 5.6 0.0 10.1 7.9 5.9 2008.6667 SEP 16.7 6.5 0.0 11.3 8.3 6.3 2008.7500 OCT 19.5 7.4 0.0 13.1 8.8 6.9 2008.8333 NOV 22.2 8.3 0.0 14.3 9.2 7.5 2008.9167 DEC 25.0 9.5 0.0 15.0 9.6 7.6 2009.0000 JAN 28.8 11.1 0.0 15.8 10.2 7.7 2009.0833 FEB 32.9 12.6 0.0 16.2 10.5 7.7 2009.1667 MAR 37.5 14.3 0.0 16.4 10.7 7.7 2009.2500 APR 41.5 16.3 0.0 16.8 10.7 7.8 2009.3333 MAY 43.9 18.3 0.0 17.1 10.9 8.0 2009.4167 JUN 46.1 20.5 0.0 17.3 11.2 8.3 2009.5000 JUL 49.0 23.0 0.0 17.5 11.6 8.6 2009.5833 AUG 51.7 25.4 0.0 18.0 12.1 9.1 2009.6667 SEP 54.1 28.1 0.0 18.2 12.6 9.8 2009.7500 OCT 56.3 31.3 0.9 17.8 13.1 10.2 2009.8333 NOV 63.3 35.0 3.1 17.2 13.3 10.3 2009.9167 DEC 71.0 38.1 4.7 16.9 13.4 10.4 2010.0000 JAN 77.8 40.3 5.9 16.9 13.6 10.4 2010.0833 FEB 85.8 42.9 7.2 17.3 13.9 10.4 2010.1667 MAR 95.5 45.6 7.9 17.9 14.0 10.1 2010.2500 APR 104.7 48.0 8.4 18.4 14.1 10.0 2010.3333 MAY 112.4 50.3 10.2 18.7 14.1 9.8 2010.4167 JUN 119.9 52.9 13.1 18.8 13.7 9.0 2010.5000 JUL 125.3 57.2 15.6 19.0 13.8 9.1 2010.5833 AUG 130.6 61.4 18.2 19.2 13.9 9.3 2010.6667 SEP 135.9 65.6 20.7 19.5 14.0 9.4 2010.7500 OCT 141.1 69.8 23.1 19.7 14.0 9.5 2010.8333 NOV 146.2 73.9 25.6 19.9 14.1 9.6 2010.9167 DEC 151.2 77.8 28.0 20.1 14.2 9.8 2011.0000 JAN 156.0 81.7 30.3 20.3 14.2 9.9 2011.0833 FEB 160.7 85.4 32.5 20.5 14.3 10.0 2011.1667 MAR 165.2 89.0 34.6 20.7 14.4 10.1 2011.2500 APR 169.4 92.4 36.6 20.8 14.4 10.2 2011.3333 MAY 173.4 95.6 38.6 21.0 14.5 10.3 2011.4167 JUN 177.2 98.5 40.3 21.2 14.5 10.4 2011.5000 JUL 180.6 101.3 42.0 21.3 14.6 10.5 2011.5833 AUG 183.8 103.8 43.5 21.4 14.6 10.5 2011.6667 SEP 186.6 106.0 44.8 21.6 14.7 10.6 2011.7500 OCT 189.0 108.0 46.0 21.7 14.7 10.7 2011.8333 NOV 191.1 109.6 47.0 21.7 14.7 10.7 2011.9167 DEC 192.7 110.9 47.7 21.8 14.7 10.7 2012.0000 JAN 193.9 111.9 48.3 21.9 14.8 10.8 2012.0833 FEB 194.6 112.4 48.7 21.9 14.8 10.8 2012.1667 MAR 194.9 112.6 48.8 21.9 14.8 10.8 2012.2500 APR 190.7 111.7 47.2 20.6 14.9 11.5 2012.3333 MAY 185.3 109.8 46.2 20.2 15.0 11.8 2012.4167 JUN 181.3 107.7 45.1 19.7 15.1 11.7 2012.5000 JUL 180.3 106.1 43.5 19.4 15.3 11.9 2012.5833 AUG 180.1 104.9 41.5 19.2 15.6 12.1 2012.6667 SEP 178.8 103.9 40.1 19.0 15.7 11.6 2012.7500 OCT 176.6 102.7 39.1 19.0 15.7 10.9 2012.8333 NOV 175.4 101.6 38.3 18.9 15.7 10.8 2012.9167 DEC 174.6 100.2 37.1 19.0 15.7 10.8 2013.0000 JAN 172.9 98.5 35.9 19.2 15.8 10.8 2013.0833 FEB 171.8 96.7 35.1 19.8 15.9 10.8 2013.1667 MAR 169.2 95.0 33.8 20.4 16.1 10.9 2013.2500 APR 164.9 93.4 32.0 21.4 16.3 10.8 2013.3333 MAY 161.5 92.2 30.8 21.9 16.5 10.7 2013.4167 JUN 157.3 91.1 30.4 21.6 16.6 10.6 2013.5000 JUL 153.1 89.9 29.1 21.3 16.4 10.3 2013.5833 AUG 149.3 88.6 27.2 21.8 16.5 10.3 2013.6667 SEP 146.5 86.9 25.5 23.1 16.7 10.4 2013.7500 OCT 145.1 85.0 24.2 23.3 16.9 10.9 2013.8333 NOV 142.6 82.8 23.3 22.7 17.0 11.7 2013.9167 DEC 139.5 80.6 22.3 22.6 17.0 11.8 2014.0000 JAN 134.9 78.5 21.1 22.7 16.9 11.9 2014.0833 FEB 132.1 76.6 19.8 23.2 17.1 12.0 2014.1667 MAR 132.2 75.0 18.3 23.9 17.3 12.1 2014.2500 APR 133.2 73.4 16.7 23.9 17.2 12.5 2014.3333 MAY 132.3 71.5 15.2 23.9 17.1 13.3 2014.4167 JUN 128.8 69.3 13.5 23.3 17.0 13.7 2014.5000 JUL 123.2 67.0 11.9 21.6 16.8 13.3 2014.5833 AUG 118.8 65.3 11.1 21.8 16.6 12.8 2014.6667 SEP 116.4 63.8 10.6 21.8 16.4 12.7 2014.7500 OCT 115.3 62.2 9.7 21.5 16.4 12.5 2014.8333 NOV 113.1 60.8 9.3 21.1 16.4 12.4 2014.9167 DEC 110.6 59.5 9.4 20.5 16.4 12.2 2015.0000 JAN 106.6 57.9 9.4 19.9 16.1 11.9 2015.0833 FEB 100.7 56.0 8.9 20.1 16.0 11.9 2015.1667 MAR 94.5 54.0 8.6 21.6 15.9 11.7 2015.2500 APR 88.4 52.2 8.2 23.2 15.8 11.7 2015.3333 MAY 83.4 50.4 8.0 24.0 15.8 11.5 2015.4167 JUN 79.8 48.4 8.5 25.1 15.7 11.3 2015.5000 JUL 76.6 46.7 9.1 25.8 15.7 11.3 2015.5833 AUG 73.3 45.5 9.5 25.0 15.6 10.8 2015.6667 SEP 71.2 44.2 9.7 25.0 15.6 10.3 2015.7500 OCT 71.4 43.1 9.3 24.1 15.7 10.7 2015.8333 NOV 71.6 41.6 8.5 22.2 15.7 10.8 2015.9167 DEC 70.0 39.9 7.7 21.4 15.6 10.8 2016.0000 JAN 68.6 38.5 7.0 21.7 15.8 11.0 2016.0833 FEB 68.8 37.4 6.2 22.4 16.0 11.2 2016.1667 MAR 68.7 36.2 5.5 22.6 16.0 11.2 2016.2500 APR 68.2 35.0 5.0 22.5 16.1 11.0 2016.3333 MAY 67.4 33.6 4.3 22.7 16.3 11.0 2016.4167 JUN 65.8 32.0 3.2 22.9 16.6 11.3 2016.5000 JUL 63.7 30.7 2.5 23.4 16.8 11.2 2016.5833 AUG 61.1 29.5 2.0 24.1 16.9 11.2 2016.6667 SEP 56.9 28.4 1.8 24.8 17.0 11.8 2016.7500 OCT 51.2 27.3 1.8 25.4 16.9 12.2 2016.8333 NOV 46.9 26.1 1.6 25.6 16.7 12.1 2016.9167 DEC 46.8 24.9 1.2 25.4 16.4 12.0 2017.0000 JAN 47.3 23.9 0.8 24.7 16.0 12.2 2017.0833 FEB 48.4 23.1 0.6 23.6 15.6 12.3 2017.1667 MAR 48.9 22.3 0.6 22.8 15.2 12.2 2017.2500 APR 47.1 21.5 0.6 22.4 14.9 11.8 2017.3333 MAY 43.6 20.8 0.5 21.9 14.6 11.2 2017.4167 JUN 40.7 19.9 0.3 21.6 14.2 10.7 2017.5000 JUL 39.0 19.1 0.2 20.9 13.8 10.0 2017.5833 AUG 38.6 18.2 0.1 20.0 13.4 9.4 2017.6667 SEP 38.0 17.3 0.0 18.7 13.1 9.0 2017.7500 OCT 37.4 16.5 0.0 18.2 12.8 8.5 2017.8333 NOV 36.5 15.7 0.0 18.7 12.6 8.0 2017.9167 DEC 35.4 15.0 0.3 18.7 12.5 7.8 2018.0000 JAN 34.4 14.4 0.8 18.4 12.4 7.4 2018.0833 FEB 33.3 13.8 1.0 18.4 12.2 7.0 2018.1667 MAR 31.7 13.0 1.3 18.8 12.1 6.6 2018.2500 APR 29.6 12.3 1.5 18.9 12.0 6.5 2018.3333 MAY 26.9 11.5 1.7 18.8 12.0 6.4 2018.4167 JUN 23.6 10.8 2.0 18.4 11.9 6.6 2018.5000 JUL 20.3 10.2 2.5 17.5 11.8 6.9 2018.5833 AUG 19.7 9.7 2.6 16.5 11.7 7.2 2018.6667 SEP 19.1 9.3 2.6 16.3 11.6 7.4 2018.7500 OCT 18.1 8.9 2.6 16.6 11.6 7.5 2018.8333 NOV 17.0 8.7 2.4 16.9 11.6 7.5 2018.9167 DEC 16.0 8.6 2.3 17.2 11.6 7.7 2019.0000 JAN 15.4 8.6 1.9 17.3 11.6 7.7 2019.0833 FEB 14.5 8.7 1.8 17.7 11.5 7.6 2019.1667 MAR 15.4 9.0 1.8 18.0 11.4 7.6 2019.2500 APR 16.5 9.4 1.8 18.2 11.4 7.6 2019.3333 MAY 18.0 9.6 1.7 18.1 11.3 7.6 2019.4167 JUN 20.0 10.0 1.7 17.8 11.2 7.5 2019.5000 JUL 22.2 10.7 2.4 17.3 11.1 7.5 2019.5833 AUG 24.5 11.8 3.0 16.3 11.0 7.5 2019.6667 SEP 27.7 13.0 3.8 15.5 10.9 7.5 2019.7500 OCT 30.9 14.3 4.0 16.1 10.8 7.7 2019.8333 NOV 34.2 15.9 4.5 16.3 10.8 7.7 2019.9167 DEC 38.3 17.8 5.2 16.6 10.9 7.8 2020.0000 JAN 43.1 19.7 5.8 16.7 11.0 7.7 2020.0833 FEB 47.9 21.7 6.2 16.8 11.1 7.7 2020.1667 MAR 52.1 23.9 7.4 17.1 11.1 7.8 2020.2500 APR 55.4 26.5 9.2 17.3 11.1 8.0 2020.3333 MAY 58.8 29.4 10.5 17.3 11.2 8.3 2020.4167 JUN 62.6 32.4 11.8 17.4 11.5 8.6 2020.5000 JUL 65.9 35.3 14.0 17.6 11.7 9.0 2020.5833 AUG 68.4 38.0 14.7 17.5 12.0 8.8 2020.6667 SEP 70.8 40.8 15.2 16.9 12.2 8.7 2020.7500 OCT 73.1 44.1 15.7 16.2 12.4 8.9 2020.8333 NOV 78.8 47.4 16.2 16.0 12.5 9.0 2020.9167 DEC 85.1 50.4 16.4 16.0 12.7 9.0 2021.0000 JAN 92.8 53.6 16.3 16.1 12.9 8.8 2021.0833 FEB 102.4 56.5 16.1 16.7 13.0 8.4 2021.1667 MAR 111.8 59.2 16.2 17.1 13.0 8.2 2021.2500 APR 119.9 62.3 16.8 17.5 13.1 8.2 2021.3333 MAY 127.9 65.5 17.2 18.2 13.2 8.1 2021.4167 JUN 136.4 68.9 17.9 18.5 13.2 7.9 2021.5000 JUL 143.1 71.8 19.3 18.5 13.1 7.8 2021.5833 AUG 146.6 74.4 20.7 18.7 13.1 7.9 2021.6667 SEP 149.9 76.5 21.1 19.0 13.2 8.1 2021.7500 OCT 154.1 78.7 22.6 18.6 13.3 8.6 2021.8333 NOV 158.4 80.9 24.4 17.8 13.3 9.2 2021.9167 DEC 163.8 83.2 26.5 18.1 13.4 9.6 2022.0000 JAN 168.2 85.7 29.0 18.9 13.5 10.1 2022.0833 FEB 169.7 88.0 30.9 19.1 13.6 10.1 2022.1667 MAR 172.7 90.3 32.1 19.5 13.9 10.3 2022.2500 APR 178.2 93.0 34.4 20.5 14.1 10.4 2022.3333 MAY 182.2 95.8 36.7 20.2 14.1 10.6 2022.4167 JUN 184.8 98.2 38.2 20.4 14.1 10.2 2022.5000 JUL 187.6 100.5 40.9 20.7 14.1 10.2 2022.5833 AUG 189.9 102.8 43.9 21.1 14.2 9.9 2022.6667 SEP 192.1 105.0 45.9 21.4 14.2 9.8 2022.7500 OCT 193.6 106.7 47.3 21.4 14.4 10.5 2022.8333 NOV 194.3 108.3 47.5 21.6 14.5 10.9 2022.9167 DEC 193.6 109.6 46.7 21.9 14.7 10.9 2023.0000 JAN 192.7 110.9 46.3 22.4 14.9 11.0 2023.0833 FEB 194.4 112.7 47.8 22.9 15.1 11.2