Year	mm per year
1961	1348
1962	1348
1963	1348
1964	1348
1965	1348
1966	1348
1967	1348
1968	1348
1969	1348
1970	1348
1971	1348
1972	1348
1973	1348
1974	1348
1975	1348
1976	1348
1977	1348
1978	1348
1979	1348
1980	1348
1981	1348
1982	1348
1983	1348
1984	1348
1985	1348
1986	1348
1987	1348
1988	1348
1989	1348
1990	1348
1991	1348
1992	1348
1993	1348
1994	1348
1995	1348
1996	1348
1997	1348
1998	1348
1999	1348
2000	1348
2001	1348
2002	1348
2003	1348
2004	1348
2005	1348
2006	1348
2007	1348
2008	1348
2009	1348
2010	1348
2011	1348
2012	1348
2013	1348
2014	1348
2015	1348
2016	1348
2017	1348
2018	1348
2019	1348
2020	1348