Year	% of land area
1990	65.43771424786236
1991	64.48467351523817
1992	63.531632782613976
1993	62.57859204998979
1994	61.6255513173656
1995	60.67251058474141
1996	59.71946985211722
1997	58.76642911949303
1998	57.813388386868844
1999	56.860347654244656
2000	53.943528667353036
2001	53.85720197771634
2002	53.770875288079644
2003	53.68454859844295
2004	53.59822190880625
2005	53.51189521916956
2006	53.42556852953285
2007	53.339241839896154
2008	53.25291515025946
2009	53.16658846062276
2010	53.08026177098607
2011	52.58691922691595
2012	52.09357668284582
2013	51.60023413877569
2014	51.10689159470556
2015	50.61354905063544
2016	50.74345452695819
2017	50.039333822986606
2018	49.71681777920756
2019	49.39429640925072
2020	49.07178036547167
2021	48.36194486812056