Year mm per year 1961 1577 1962 1577 1963 1577 1964 1577 1965 1577 1966 1577 1967 1577 1968 1577 1969 1577 1970 1577 1971 1577 1972 1577 1973 1577 1974 1577 1975 1577 1976 1577 1977 1577 1978 1577 1979 1577 1980 1577 1981 1577 1982 1577 1983 1577 1984 1577 1985 1577 1986 1577 1987 1577 1988 1577 1989 1577 1990 1577 1991 1577 1992 1577 1993 1577 1994 1577 1995 1577 1996 1577 1997 1577 1998 1577 1999 1577 2000 1577 2001 1577 2002 1577 2003 1577 2004 1577 2005 1577 2006 1577 2007 1577 2008 1577 2009 1577 2010 1577 2011 1577 2012 1577 2013 1577 2014 1577 2015 1577 2016 1577 2017 1577 2018 1577 2019 1577 2020 1577