Year	% of land area
1990	0.17027431421446385
1991	0.18300249376558606
1992	0.19573067331670824
1993	0.20845885286783045
1994	0.22118703241895263
1995	0.2339152119700748
1996	0.24664339152119702
1997	0.25937157107231923
1998	0.2720997506234413
1999	0.28482793017456365
2000	0.2975561097256858
2001	0.312359102244389
2002	0.32716209476309227
2003	0.3419650872817955
2004	0.3567680798004988
2005	0.371571072319202
2006	0.3863740648379052
2007	0.40117705735660847
2008	0.4159800498753117
2009	0.430783042394015
2010	0.4455860349127182
2011	0.4525486284289277
2012	0.4595112219451372
2013	0.4664738154613466
2014	0.4734364089775562
2015	0.4803990024937656
2016	0.48538653366583545
2017	0.49256857855361597
2018	0.49628086878905087
2019	0.5027273628880293
2020	0.5092730338192998
2021	0.5157522562729346