Year	% of land area
1961	17.013437364542696
1962	17.013437364542696
1963	17.049559312238117
1964	17.049559312238117
1965	17.085681259933537
1966	17.085681259933537
1967	17.121803207628954
1968	17.103742233781247
1969	17.320473919953763
1970	17.53720560612628
1971	17.7539372922988
1972	17.97066897847132
1973	18.18740066464384
1974	18.66782256899292
1975	19.45166883398353
1976	20.065741944805666
1977	21.077156480277417
1978	21.691229591099553
1979	22.359485623464817
1980	23.399797717092905
1981	24.414824447334198
1982	25.140875596012137
1983	25.628521889900302
1984	26.20647305302702
1985	26.802485190001445
1986	27.38043635312816
1987	27.889755815633578
1988	27.907816789481288
1989	28.00534604825892
1990	28.341280161826326
1991	28.58690940615518
1992	28.727785002167316
1993	28.80725328709724
1994	29.363531281606704
1995	29.287675191446322
1996	28.850599624331746
1997	28.94090449357029
1998	32.3200193267837
1999	32.51328716379449
2000	32.47704944435497
2001	31.34562731518763
2002	30.15783540022548
2003	29.191496215171526
2004	30.30681269125463
2005	30.198099532936062
2006	29.972620389756806
2007	29.843775165082942
2008	29.97664680302786
2009	30.33660814946046
2010	30.188838782412624
2011	29.578434530520216
2012	30.225881784506363
2013	30.250442905459817
2014	22.044612659043324
2015	23.30890642615558
2016	22.209695603156707
2017	22.507650185215013
2018	21.935899500724755
2019	21.460782734739894
2020	21.823159929135127
2021	22.024480592688032