Year	% of land area
1990	31.076465862562753
1991	30.937884130668795
1992	30.799302398774845
1993	30.66072066688089
1994	30.52213893498694
1995	30.383557203092984
1996	30.24497547119903
1997	30.10639373930508
1998	29.967812007411123
1999	29.829230275517173
2000	29.690648543623215
2001	29.544295581843382
2002	29.397942620063546
2003	29.251589658283713
2004	28.923273270076763
2005	28.777780597788
2006	28.632352344016947
2007	28.48685896326592
2008	28.341466548314493
2009	28.195990420954374
2010	28.04974117137759
2011	27.88473572961515
2012	27.57622962525059
2013	27.412417047333996
2014	27.24861426498077
2015	27.084696879543245
2016	26.916630679933743
2017	26.75202759424436
2018	26.587526808236436
2019	26.418755014894153
2020	26.25170732918735
2021	26.08350204256289