Year % of land area 1961 4.3927648578811365 1962 4.3927648578811365 1963 4.3927648578811365 1964 4.3927648578811365 1965 4.3927648578811365 1966 4.3927648578811365 1967 4.3927648578811365 1968 4.3927648578811365 1969 4.3927648578811365 1970 4.3927648578811365 1971 4.3927648578811365 1972 4.3927648578811365 1973 4.3927648578811365 1974 4.478897502153316 1975 4.478897502153316 1976 4.478897502153316 1977 4.478897502153316 1978 4.478897502153316 1979 4.565030146425495 1980 4.7372954349698535 1981 4.823428079242033 1982 4.909560723514212 1983 4.995693367786391 1984 5.0818260120585705 1985 5.0818260120585705 1986 5.167958656330749 1987 5.254091300602928 1988 5.254091300602928 1989 5.167958656330749 1990 5.254091300602928 1991 5.254091300602928 1992 5.512489233419466 1993 5.598621877691645 1994 5.598621877691645 1995 5.598621877691645 1996 5.684754521963824 1997 5.684754521963824 1998 5.684754521963824 1999 5.684754521963824 2000 5.684754521963824 2001 5.710594315245478 2002 5.658914728682171 2003 5.701981050818261 2004 5.615848406546081 2005 5.564168819982774 2006 5.624461670973299 2007 5.684754521963824 2008 5.74504737295435 2009 5.805340223944875 2010 5.8656330749354 2011 5.9259259259259265 2012 5.986218776916451 2013 6.046511627906977 2014 6.179286335944299 2015 6.179286335944299 2016 6.179286335944299 2017 6.266318537859007 2018 6.440382941688425 2019 6.440382941688425 2020 6.440382941688425 2021 6.440382941688425