Year	mm per year
1961	2702
1962	2702
1963	2702
1964	2702
1965	2702
1966	2702
1967	2702
1968	2702
1969	2702
1970	2702
1971	2702
1972	2702
1973	2702
1974	2702
1975	2702
1976	2702
1977	2702
1978	2702
1979	2702
1980	2702
1981	2702
1982	2702
1983	2702
1984	2702
1985	2702
1986	2702
1987	2702
1988	2702
1989	2702
1990	2702
1991	2702
1992	2702
1993	2702
1994	2702
1995	2702
1996	2702
1997	2702
1998	2702
1999	2702
2000	2702
2001	2702
2002	2702
2003	2702
2004	2702
2005	2702
2006	2702
2007	2702
2008	2702
2009	2702
2010	2702
2011	2702
2012	2702
2013	2702
2014	2702
2015	2702
2016	2702
2017	2702
2018	2702
2019	2702
2020	2702