Year	% of land area
1990	56.94085389737563
1991	56.84257735996866
1992	56.74430082256169
1993	56.646024285154716
1994	56.54774774774774
1995	56.449471210340775
1996	56.3511946729338
1997	56.25291813552683
1998	56.15464159811986
1999	56.056365060712885
2000	55.95808852330592
2001	55.98546807677243
2002	56.01284763023894
2003	56.04022718370545
2004	56.06760673717195
2005	56.09498629063846
2006	56.12236584410498
2007	56.14974539757148
2008	56.177124951037996
2009	56.204504504504506
2010	56.231884057971016
2011	56.5524089306698
2012	56.87293380336859
2013	57.193458676067365
2014	57.513983548766156
2015	57.83450842146494
2016	58.1551116333725
2017	58.475714845280066
2018	58.79612220916569
2019	59.11672542107325
2020	59.437328632980815
2021	59.75793184488837