Year	mm per year
1961	2350
1962	2350
1963	2350
1964	2350
1965	2350
1966	2350
1967	2350
1968	2350
1969	2350
1970	2350
1971	2350
1972	2350
1973	2350
1974	2350
1975	2350
1976	2350
1977	2350
1978	2350
1979	2350
1980	2350
1981	2350
1982	2350
1983	2350
1984	2350
1985	2350
1986	2350
1987	2350
1988	2350
1989	2350
1990	2350
1991	2350
1992	2350
1993	2350
1994	2350
1995	2350
1996	2350
1997	2350
1998	2350
1999	2350
2000	2350
2001	2350
2002	2350
2003	2350
2004	2350
2005	2350
2006	2350
2007	2350
2008	2350
2009	2350
2010	2350
2011	2350
2012	2350
2013	2350
2014	2350
2015	2350
2016	2350
2017	2350
2018	2350
2019	2350
2020	2350