Year % of land area 1961 49.308176100628934 1962 49.937106918238996 1963 49.937106918238996 1964 50.25157232704402 1965 50.56603773584906 1966 50.56603773584906 1967 50.786163522012586 1968 50.786163522012586 1969 50.943396226415096 1970 50.943396226415096 1971 51.257861635220124 1972 51.28930817610063 1973 51.698113207547166 1974 52.27987421383647 1975 52.56289308176101 1976 52.9559748427673 1977 53.71069182389937 1978 54.119496855345915 1979 54.166666666666664 1980 54.26100628930818 1981 54.62264150943397 1982 55.00000000000001 1983 55.295597484276726 1984 56.29245283018868 1985 57.16981132075472 1986 57.484276729559745 1987 57.861635220125784 1988 58.867924528301884 1989 59.18238993710692 1990 59.528301886792455 1991 59.59119496855346 1992 60.37735849056604 1993 61.32704402515723 1994 61.94968553459119 1995 62.264150943396224 1996 62.264150943396224 1997 61.94968553459119 1998 61.94968553459119 1999 61.63522012578616 2000 61.63522012578616 2001 61.63522012578616 2002 61.63522012578616 2003 61.63522012578616 2004 62.893081761006286 2005 63.52201257861635 2006 63.83647798742138 2007 64.77987421383648 2008 64.77987421383648 2009 64.77987421383648 2010 64.77987421383648 2011 64.77987421383648 2012 65.09433962264151 2013 66.66666666666666 2014 67.13836477987421 2015 69.81132075471697 2016 68.86792452830188 2017 69.18238993710692 2018 72.79874213836479 2019 73.0503144654088 2020 73.27044025157232 2021 73.89937106918238