Year	mm per year
1961	1834
1962	1834
1963	1834
1964	1834
1965	1834
1966	1834
1967	1834
1968	1834
1969	1834
1970	1834
1971	1834
1972	1834
1973	1834
1974	1834
1975	1834
1976	1834
1977	1834
1978	1834
1979	1834
1980	1834
1981	1834
1982	1834
1983	1834
1984	1834
1985	1834
1986	1834
1987	1834
1988	1834
1989	1834
1990	1834
1991	1834
1992	1834
1993	1834
1994	1834
1995	1834
1996	1834
1997	1834
1998	1834
1999	1834
2000	1834
2001	1834
2002	1834
2003	1834
2004	1834
2005	1834
2006	1834
2007	1834
2008	1834
2009	1834
2010	1834
2011	1834
2012	1834
2013	1834
2014	1834
2015	1834
2016	1834
2017	1834
2018	1834
2019	1834
2020	1834