Year	mm per year
1961	1705
1962	1705
1963	1705
1964	1705
1965	1705
1966	1705
1967	1705
1968	1705
1969	1705
1970	1705
1971	1705
1972	1705
1973	1705
1974	1705
1975	1705
1976	1705
1977	1705
1978	1705
1979	1705
1980	1705
1981	1705
1982	1705
1983	1705
1984	1705
1985	1705
1986	1705
1987	1705
1988	1705
1989	1705
1990	1705
1991	1705
1992	1705
1993	1705
1994	1705
1995	1705
1996	1705
1997	1705
1998	1705
1999	1705
2000	1705
2001	1705
2002	1705
2003	1705
2004	1705
2005	1705
2006	1705
2007	1705
2008	1705
2009	1705
2010	1705
2011	1705
2012	1705
2013	1705
2014	1705
2015	1705
2016	1705
2017	1705
2018	1705
2019	1705
2020	1705