Year	% of land area
1992	21.67769629762118
1993	18.994813092470043
1994	19.74602038991236
1995	19.97853693435879
1996	17.61343336906038
1997	17.559842801000357
1998	19.47773206939725
1999	19.102128420676088
2000	15.059379024180855
2001	15.256116754900559
2002	15.345542996136786
2003	15.438496176113215
2004	15.134729468944322
2005	15.599313844614397
2006	15.742262883282109
2007	15.224072618111641
2008	15.379529697662782
2009	15.515331284397114
2010	16.160388821385176
2011	16.0228003716675
2012	16.196126081052107
2013	15.660067186048174
2014	14.525409191623186
2015	15.075762990493887
2016	15.61718247444786
2017	14.598670573940389
2018	14.366378386105353
2019	14.705882352941178
2020	15.886347390993565
2021	15.314510364546106