Year	% of land area
1990	33.216151394684104
1991	33.21094939273472
1992	33.20574739078534
1993	33.200545388835955
1994	33.19534338688657
1995	33.19014138493719
1996	33.18493938298781
1997	33.17973738103843
1998	33.17453537908905
1999	33.169333377139665
2000	33.16413137519028
2001	33.16111968985117
2002	33.15810800451205
2003	33.15509631917294
2004	33.15208463383382
2005	33.149072948494705
2006	33.14606126315559
2007	33.14304957781648
2008	33.14003789247736
2009	33.13702620713824
2010	33.13401452179912
2011	33.155370108749224
2012	33.17672569569931
2013	33.20908660468791
2014	33.23181086144374
2015	33.24564398819575
2016	33.271099733248974
2017	33.29453362291611
2018	33.317265028429944
2019	33.339906982859205
2020	33.43535967717584
2021	33.45814917506245