Year	mm per year
1961	1732
1962	1732
1963	1732
1964	1732
1965	1732
1966	1732
1967	1732
1968	1732
1969	1732
1970	1732
1971	1732
1972	1732
1973	1732
1974	1732
1975	1732
1976	1732
1977	1732
1978	1732
1979	1732
1980	1732
1981	1732
1982	1732
1983	1732
1984	1732
1985	1732
1986	1732
1987	1732
1988	1732
1989	1732
1990	1732
1991	1732
1992	1732
1993	1732
1994	1732
1995	1732
1996	1732
1997	1732
1998	1732
1999	1732
2000	1732
2001	1732
2002	1732
2003	1732
2004	1732
2005	1732
2006	1732
2007	1732
2008	1732
2009	1732
2010	1732
2011	1732
2012	1732
2013	1732
2014	1732
2015	1732
2016	1732
2017	1732
2018	1732
2019	1732
2020	1732