Year	% of land area
1990	27.703833509930178
1991	27.74414533106961
1992	31.515461970585864
1993	32.09601640606829
1994	32.14796286358367
1995	32.20194445726511
1996	32.25242537465376
1997	32.30728201861114
1998	32.360972175340514
1999	32.41407663272813
2000	32.46947199423694
2001	32.593462803028864
2002	32.76697613248992
2003	32.88930640107816
2004	33.01018694646257
2005	33.13885079682159
2006	33.2639312747045
2007	33.391439845320036
2008	33.51620278504829
2009	33.609941948725265
2010	33.73459167252943
2011	33.86417788661386
2012	34.00071029475421
2013	34.099423226925005
2014	34.20840789950816
2015	34.33997784119086
2016	34.39391422693465
2017	34.47108402216233
2018	34.500882027648274
2019	34.53188703746422
2020	34.55928472644914
2021	34.58928003676681