Year % of land area 1961 3.9244186046511627 1962 3.9036544850498336 1963 3.9036544850498336 1964 3.8725083056478407 1965 3.8725083056478407 1966 3.8413621262458473 1967 3.8413621262458473 1968 3.820598006644518 1969 3.820598006644518 1970 3.799833887043189 1971 3.799833887043189 1972 3.799833887043189 1973 3.799833887043189 1974 3.799833887043189 1975 3.799833887043189 1976 3.799833887043189 1977 3.8517441860465116 1978 3.8517441860465116 1979 3.8517441860465116 1980 3.8517441860465116 1981 3.8517441860465116 1982 3.8932724252491697 1983 3.9451827242524917 1984 3.9451827242524917 1985 3.9451827242524917 1986 4.049003322259137 1987 4.049003322259137 1988 4.152823920265781 1989 4.152823920265781 1990 3.6337209302325584 1991 3.6337209302325584 1992 3.6337209302325584 1993 3.6337209302325584 1994 3.6337209302325584 1995 3.6337209302325584 1996 3.6337209302325584 1997 3.8413621262458473 1998 3.9451827242524917 1999 4.152823920265781 2000 4.152823920265781 2001 4.152823920265781 2002 4.152823920265781 2003 4.152823920265781 2004 4.152823920265781 2005 4.152823920265781 2006 4.152823920265781 2007 4.152823920265781 2008 4.464285714285714 2009 4.879568106312292 2010 4.983388704318937 2011 5.191029900332226 2012 5.191029900332226 2013 5.191029900332226 2014 5.191029900332226 2015 5.191029900332226 2016 5.191029900332226 2017 5.191029900332226 2018 5.191029900332226 2019 5.191029900332226 2020 5.191029900332226 2021 5.191029900332226