Year	% of land area
1990	32.275570723816564
1991	32.28086298650577
1992	32.35700562670959
1993	32.37634847524773
1994	32.38224532874594
1995	32.388142188361094
1996	32.394131552323415
1997	32.40011181843732
1998	32.406028176086394
1999	32.41195367909287
2000	32.40550504186902
2001	32.42077826681381
2002	32.43533925045636
2003	32.45002772923027
2004	32.46532841414652
2005	32.480482992910595
2006	32.49609522848931
2007	32.51104881363335
2008	32.53983744011151
2009	32.554072437841285
2010	32.56780045736002
2011	32.602849332965846
2012	32.63730662962313
2013	32.67088348092914
2014	32.705092492374376
2015	32.74041813130559
2016	32.75612585182722
2017	32.75002038098476
2018	32.75231283991358
2019	32.75572960879652
2020	32.760247874918235
2021	32.92768005481114