Year	% of land area
1992	29.98107703224789
1993	30.084971314788163
1994	30.683464939520306
1995	30.719482619240097
1996	30.71174342137695
1997	30.440462399250695
1998	30.503527602068736
1999	30.477974708506917
2000	30.234461271493927
2001	28.401135848238056
2002	27.688348313111042
2003	27.457032135919455
2004	27.3549786751473
2005	27.322970128134966
2006	27.303552418877892
2007	27.20045736590751
2008	27.185537845856622
2009	27.324074165344165
2010	27.279179111097967
2011	27.248533832733724
2012	27.21551116565385
2013	27.400102509511697
2014	27.895828509210585
2015	27.97051897249948
2016	28.000669990344257
2017	28.213490452637597
2018	28.14070351758794
2019	28.147710196339272
2020	27.884520642427823
2021	27.711258930771127