Year	% of land area
1990	36.31351114997814
1991	36.19980966588647
1992	36.0861081817948
1993	35.97240669770313
1994	35.858705213611465
1995	35.745003729519794
1996	35.63130224542812
1997	35.51760076133645
1998	35.40389927724478
1999	35.29019779315312
2000	35.17649630906144
2001	35.102521155379506
2002	35.02854600169758
2003	34.954570848015635
2004	34.8805956943337
2005	34.806620540651764
2006	34.73264538696983
2007	34.65867023328789
2008	34.58469507960596
2009	34.51071992592402
2010	34.436744772242086
2011	34.37373903649785
2012	34.31073330075362
2013	34.247727565009384
2014	34.18472182926516
2015	34.121716093520924
2016	34.05599423853494
2017	33.99026723938373
2018	33.92454024023252
2019	33.858818385246536
2020	33.79309138609533
2021	33.727367833534814