Year	mm per year
1961	416
1962	416
1963	416
1964	416
1965	416
1966	416
1967	416
1968	416
1969	416
1970	416
1971	416
1972	416
1973	416
1974	416
1975	416
1976	416
1977	416
1978	416
1979	416
1980	416
1981	416
1982	416
1983	416
1984	416
1985	416
1986	416
1987	416
1988	416
1989	416
1990	416
1991	416
1992	416
1993	416
1994	416
1995	416
1996	416
1997	416
1998	416
1999	416
2000	416
2001	416
2002	416
2003	416
2004	416
2005	416
2006	416
2007	416
2008	416
2009	416
2010	416
2011	416
2012	416
2013	416
2014	416
2015	416
2016	416
2017	416
2018	416
2019	416
2020	416