Year	% of land area
1992	27.126488501775757
1993	27.110418307165702
1994	27.480032783197007
1995	16.10233499927684
1996	17.03440628666013
1997	17.33973998425121
1998	17.018336092050074
1999	15.86128208012599
2000	15.588088771755027
2001	15.395246436434345
2002	15.636299355585196
2003	15.379176241824288
2004	16.21482636154724
2005	17.54865251418195
2006	19.36458450511836
2007	19.09139119674739
2008	18.802127693766373
2009	18.769987304546255
2010	18.850338277596542
2011	18.60928535844569
2012	18.930689250646825
2013	19.412795088948528
2014	19.428865283558583
2015	19.763125331447764
2016	20.698410657753065
2017	20.73055104697318
2018	20.810902020023462
2019	21.196586690664823
2020	21.4366061385184
2021	21.88654989554877