Year	mm per year
1962	1500
1963	1500
1964	1500
1965	1500
1966	1500
1967	1500
1968	1500
1969	1500
1970	1500
1971	1500
1972	1500
1973	1500
1974	1500
1975	1500
1976	1500
1977	1500
1978	1500
1979	1500
1980	1500
1981	1500
1982	1500
1983	1500
1984	1500
1985	1500
1986	1500
1987	1500
1988	1500
1989	1500
1990	1500
1991	1500
1992	1500
1993	1500
1994	1500
1995	1500
1996	1500
1997	1500
1998	1500
1999	1500
2000	1500
2001	1500
2002	1500
2003	1500
2004	1500
2005	1500
2006	1500
2007	1500
2008	1500
2009	1500
2010	1500
2011	1500
2012	1500
2013	1500
2014	1500
2015	1500
2016	1500
2017	1500
2018	1500
2019	1500
2020	1500