Year % of land area 1961 1.5686274509803921 1962 1.4973262032085561 1963 1.4616755793226381 1964 1.3903743315508021 1965 1.3547237076648841 1966 1.2834224598930482 1967 1.2477718360071302 1968 1.1764705882352942 1969 1.1408199643493762 1970 1.06951871657754 1971 1.033868092691622 1972 1.1051693404634582 1973 1.06951871657754 1974 0.9982174688057042 1975 0.9625668449197862 1976 0.8912655971479502 1977 0.8556149732620321 1978 0.7843137254901961 1979 0.7486631016042781 1980 0.6773618538324421 1981 0.6417112299465241 1982 0.5704099821746881 1983 0.53475935828877 1984 0.53475935828877 1985 0.53475935828877 1986 0.53475935828877 1987 0.53475935828877 1988 0.53475935828877 1989 0.53475935828877 1990 0.5704099821746881 1991 0.5704099821746881 1992 0.6060606060606061 1993 0.6060606060606061 1994 0.6060606060606061 1995 0.6060606060606061 1996 0.6417112299465241 1997 0.6773618538324421 1998 0.7130124777183601 1999 0.7130124777183601 2000 0.7843137254901961 2001 1.06951871657754 2002 1.3190730837789661 2003 1.3190730837789661 2004 1.3190730837789661 2005 1.3190730837789661 2006 1.4616755793226381 2007 1.4616755793226381 2008 1.6399286987522281 2009 1.9251336898395723 2010 1.9251336898395723 2011 1.9251336898395723 2012 1.9251336898395723 2013 1.9251336898395723 2014 1.9251336898395723 2015 1.9251336898395723 2016 1.9251336898395723 2017 1.9251336898395723 2018 1.9251336898395723 2019 1.8894830659536541 2020 1.8894830659536541 2021 1.8894830659536541