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