Year	mm per year
1961	1651
1962	1651
1963	1651
1964	1651
1965	1651
1966	1651
1967	1651
1968	1651
1969	1651
1970	1651
1971	1651
1972	1651
1973	1651
1974	1651
1975	1651
1976	1651
1977	1651
1978	1651
1979	1651
1980	1651
1981	1651
1982	1651
1983	1651
1984	1651
1985	1651
1986	1651
1987	1651
1988	1651
1989	1651
1990	1651
1991	1651
1992	1651
1993	1651
1994	1651
1995	1651
1996	1651
1997	1651
1998	1651
1999	1651
2000	1651
2001	1651
2002	1651
2003	1651
2004	1651
2005	1651
2006	1651
2007	1651
2008	1651
2009	1651
2010	1651
2011	1651
2012	1651
2013	1651
2014	1651
2015	1651
2016	1651
2017	1651
2018	1651
2019	1651
2020	1651