Year	mm per year
1961	1410
1962	1410
1963	1410
1964	1410
1965	1410
1966	1410
1967	1410
1968	1410
1969	1410
1970	1410
1971	1410
1972	1410
1973	1410
1974	1410
1975	1410
1976	1410
1977	1410
1978	1410
1979	1410
1980	1410
1981	1410
1982	1410
1983	1410
1984	1410
1985	1410
1986	1410
1987	1410
1988	1410
1989	1410
1990	1410
1991	1410
1992	1410
1993	1410
1994	1410
1995	1410
1996	1410
1997	1410
1998	1410
1999	1410
2000	1410
2001	1410
2002	1410
2003	1410
2004	1410
2005	1410
2006	1410
2007	1410
2008	1410
2009	1410
2010	1410
2011	1410
2012	1410
2013	1410
2014	1410
2015	1410
2016	1410
2017	1410
2018	1410
2019	1410
2020	1410