Year	% of land area
1992	31.26994256541161
1993	31.389597957881303
1994	31.509253350350992
1995	31.628908742820677
1996	31.748564135290362
1997	31.86821952776005
1998	31.987874920229736
1999	32.10753031269943
2000	32.22718570516911
2001	32.46649649010849
2002	32.70580727504786
2003	32.94511805998724
2004	33.184428844926614
2005	33.423739629865985
2006	33.66305041480536
2007	33.90236119974473
2008	34.144395692062226
2009	34.38372556840846
2010	34.623055444754684
2011	34.677856846539235
2012	34.732105817404346
2013	34.78579976067012
2014	34.85395051875499
2015	34.90822027134876
2016	34.960569585900835
2017	35.056911607413674
2018	35.09500239501836
2019	35.13254551261578
2020	35.148514851485146
2021	35.180749081616355