Year	% of land area
1992	32.41330502477
1993	31.139419674451524
1994	25.97310686482661
1995	23.37815522528898
1996	23.708421797593772
1997	24.13305024769993
1998	24.60485963670677
1999	23.614059919792403
2000	23.260202878037273
2001	20.995517810804433
2002	16.470865770228826
2003	19.549422033498466
2004	18.174097664543524
2005	20.804435008256664
2006	21.196036801132344
2007	21.57584335928285
2008	21.391837697570182
2009	21.981599433828734
2010	22.38263741448455
2011	22.31658410002359
2012	22.550129747581977
2013	22.199217851391765
2014	22.406257188865887
2015	22.843340234644582
2016	23.07338394294916
2017	22.970760233918128
2018	23.04093567251462
2019	23.120467836257312
2020	23.04093567251462
2021	23.087719298245617