Year	% of land area
1992	36.22139205662604
1993	36.400511207235546
1994	36.57963035784507
1995	36.75874950845458
1996	36.937868659064094
1997	37.11698780967361
1998	37.296106960283126
1999	37.47522611089265
2000	37.654345261502165
2001	37.66567046795124
2002	37.67699567440032
2003	37.68832088084939
2004	37.69964608729847
2005	37.71097129374754
2006	37.72229650019662
2007	38.032738803012286
2008	38.044153785176384
2009	38.070658207771615
2010	38.08207771609833
2011	38.35146708961142
2012	38.620856463124504
2013	38.8902458366376
2014	39.159635210150675
2015	39.42902458366376
2016	39.7172878667724
2017	39.7101506740682
2018	39.7101506740682
2019	39.7101506740682
2020	39.7101506740682
2021	39.7101506740682