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Table 1.
Sunspot cycle lengths (in years) and dates (fractional years, and year and month) of (starting) sunspot minima for SSN1 (NGDC 2013).
| Sunspot cycle | SSN1 fractional | Year and month | Cycle length |
|---|---|---|---|
| number | year of minimum | of SSN1 min | (years) |
| 1 | 1755.2 | 1775 March | 11.3 |
| 2 | 1766.5 | 1766 June | 9.0 |
| 3 | 1775.5 | 1775 June | 9.2 |
| 4 | 1784.7 | 1784 September | 13.7 |
| 5 | 1798.4 | 1798 May | 12.2 |
| 6 | 1810.6 | 1810 August | 12.7 |
| 7 | 1823.3 | 1823 April | 10.6 |
| 8 | 1833.9 | 1833 November | 9.6 |
| 9 | 1843.5 | 1843 July | 12.5 |
| 10 | 1856.0 | 1855 December | 11.2 |
| 11 | 1867.2 | 1867 March | 11.8 |
| 12 | 1879.0 | 1878 December | 10.6 |
| 13 | 1889.6 | 1889 August | 12.1 |
| 14 | 1901.7 | 1901 September | 11.8 |
| 15 | 1913.5 | 1913 July | 10.1 |
| 16 | 1923.6 | 1923 August | 10.1 |
| 17 | 1933.7 | 1933 September | 10.4 |
| 18 | 1944.1 | 1944 February | 10.2 |
| 19 | 1954.3 | 1954 April | 10.5 |
| 20 | 1964.8 | 1964 October | 11.7 |
| 21 | 1976.5 | 1976 June | 10.2 |
| 22 | 1986.7 | 1986 September | 10.1 |
| 23 | 1996.8 | 1996 October | 12.2 |
| 24 | 2009.0 | 2008 December |
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