Year	% of land area
1990	29.11828369388658
1991	29.107906358620397
1992	29.093000419441566
1993	29.07809447398272
1994	29.063188528523884
1995	29.04830082543019
1996	29.03341310991751
1997	29.01850714573675
1998	29.003601181555982
1999	28.98869521737522
2000	28.88036776844053
2001	28.999271168692143
2002	29.119204037480316
2003	29.225775565173056
2004	29.345341532056693
2005	29.459256106723423
2006	29.572436139481216
2007	29.691645014170753
2008	29.8104509290581
2009	29.929386975495156
2010	30.047648779068638
2011	30.0826734242213
2012	30.117597426630134
2013	30.153561610876416
2014	30.187862360001677
2015	30.222821423840706
2016	30.350619558445466
2017	30.351539433916862
2018	30.399551166050607
2019	30.447528999176544
2020	30.495095779512813
2021	30.51437755444403