year	Number of spotless days (SILSO)
1849	1
1850	7
1851	0
1852	4
1853	6
1854	70
1855	234
1856	261
1857	70
1858	2
1859	0
1860	0
1861	2
1862	4
1863	2
1864	7
1865	44
1866	86
1867	222
1868	37
1869	2
1870	0
1871	0
1872	0
1873	14
1874	12
1875	131
1876	190
1877	140
1878	280
1879	217
1880	33
1881	5
1882	2
1883	4
1884	0
1885	13
1886	62
1887	104
1888	150
1889	212
1890	171
1891	24
1892	0
1893	0
1894	0
1895	1
1896	7
1897	32
1898	39
1899	104
1900	158
1901	287
1902	257
1903	45
1904	1
1905	3
1906	4
1907	0
1908	4
1909	6
1910	75
1911	200
1912	254
1913	311
1914	153
1915	12
1916	4
1917	0
1918	0
1919	0
1920	7
1921	46
1922	134
1923	200
1924	116
1925	29
1926	2
1927	0
1928	0
1929	0
1930	3
1931	43
1932	108
1933	240
1934	154
1935	20
1936	0
1937	0
1938	0
1939	0
1940	0
1941	5
1942	24
1943	65
1944	159
1945	16
1946	0
1947	0
1948	0
1949	0
1950	3
1951	0
1952	23
1953	131
1954	241
1955	48
1956	0
1957	0
1958	0
1959	0
1960	0
1961	6
1962	10
1963	21
1964	112
1965	70
1966	8
1967	0
1968	0
1969	0
1970	0
1971	0
1972	0
1973	27
1974	20
1975	95
1976	105
1977	25
1978	0
1979	0
1980	0
1981	0
1982	0
1983	4
1984	13
1985	83
1986	129
1987	44
1988	0
1989	0
1990	0
1991	0
1992	0
1993	0
1994	19
1995	61
1996	165
1997	61
1998	3
1999	0
2000	0
2001	0
2002	0
2003	0
2004	3
2005	13
2006	65
2007	163
2008	265
2009	262
2010	44
2011	2
2012	0
2013	0
2014	1
2015	0
2016	27
2017	96
2018	208
2019	274
2020	192
2021	50
2022*   0