Year	% of land area
1990	9.274680548226835
1991	9.268987269545821
1992	9.26329399086481
1993	9.2576007121838
1994	9.251907433502787
1995	9.246214154821777
1996	9.240520876140764
1997	9.234827597459752
1998	9.22913431877874
1999	9.223441040097729
2000	9.217747761416717
2001	9.212577928335207
2002	9.207406750532341
2003	9.1593411587666
2004	9.15562080463703
2005	9.150473846151344
2006	9.127623360313835
2007	9.122486788807107
2008	9.117315128618355
2009	9.11217830189963
2010	9.10805179300629
2011	9.107573136975503
2012	9.10685778009617
2013	9.106135944111069
2014	9.10542135370957
2015	9.10469149761818
2016	9.103978705098728
2017	9.103265912579275
2018	9.102555458161959
2019	9.10182513109581
2020	9.09965848797644
2021	9.09894465963877