Year	% of land area
1992	28.003972194637537
1993	27.805362462760673
1994	27.2591857000993
1995	26.713008937437934
1996	26.067527308838134
1997	24.57795431976167
1998	24.32969215491559
1999	24.826216484607748
2000	25.719960278053627
2001	25.322740814299898
2002	25.074478649453823
2003	25.322740814299898
2004	24.42899702085402
2005	25.273088381330684
2006	24.37934458788481
2007	24.726911618669316
2008	30.70355699834212
2009	31.029792810412093
2010	30.966633906146075
2011	30.805618981435522
2012	30.368267173640035
2013	30.298411122144987
2014	30.528301886792452
2015	30.606277243255587
2016	30.6563399860987
2017	30.541113610519368
2018	30.392721638425936
2019	30.406626805188612
2020	30.317733060527203
2021	30.341073876164558