Year	% of land area
1990	28.78832116788321
1991	28.717153284671532
1992	28.645985401459857
1993	28.574817518248175
1994	28.5036496350365
1995	28.432481751824817
1996	28.361313868613138
1997	28.29014598540146
1998	28.21897810218978
1999	28.147810218978105
2000	28.076642335766422
2001	28.123248175182486
2002	28.16985401459854
2003	28.2164598540146
2004	28.263065693430654
2005	28.309671532846714
2006	28.356277372262774
2007	28.40288321167883
2008	28.44948905109489
2009	28.496094890510946
2010	28.542700729927006
2011	28.594653284671534
2012	28.646605839416058
2013	28.698558394160585
2014	28.750510948905113
2015	28.802463503649633
2016	28.802189781021898
2017	28.792062043795617
2018	28.791970802919707
2019	28.791970802919707
2020	28.791970802919707
2021	28.791970802919707