Year mm per year 1961 1168 1962 1168 1963 1168 1964 1168 1965 1168 1966 1168 1967 1168 1968 1168 1969 1168 1970 1168 1971 1168 1972 1168 1973 1168 1974 1168 1975 1168 1976 1168 1977 1168 1978 1168 1979 1168 1980 1168 1981 1168 1982 1168 1983 1168 1984 1168 1985 1168 1986 1168 1987 1168 1988 1168 1989 1168 1990 1168 1991 1168 1992 1168 1993 1168 1994 1168 1995 1168 1996 1168 1997 1168 1998 1168 1999 1168 2000 1168 2001 1168 2002 1168 2003 1168 2004 1168 2005 1168 2006 1168 2007 1168 2008 1168 2009 1168 2010 1168 2011 1168 2012 1168 2013 1168 2014 1168 2015 1168 2016 1168 2017 1168 2018 1168 2019 1168 2020 1168