Year	mm per year
1961	1150
1962	1150
1963	1150
1964	1150
1965	1150
1966	1150
1967	1150
1968	1150
1969	1150
1970	1150
1971	1150
1972	1150
1973	1150
1974	1150
1975	1150
1976	1150
1977	1150
1978	1150
1979	1150
1980	1150
1981	1150
1982	1150
1983	1150
1984	1150
1985	1150
1986	1150
1987	1150
1988	1150
1989	1150
1990	1150
1991	1150
1992	1150
1993	1150
1994	1150
1995	1150
1996	1150
1997	1150
1998	1150
1999	1150
2000	1150
2001	1150
2002	1150
2003	1150
2004	1150
2005	1150
2006	1150
2007	1150
2008	1150
2009	1150
2010	1150
2011	1150
2012	1150
2013	1150
2014	1150
2015	1150
2016	1150
2017	1150
2018	1150
2019	1150
2020	1150