Year	% of land area
1990	48.13296398891967
1991	48.130378578024015
1992	48.127793167128345
1993	48.12520775623268
1994	48.12262234533703
1995	48.120036934441366
1996	48.117451523545704
1997	48.11486611265005
1998	48.112280701754386
1999	48.109695290858724
2000	48.10710987996307
2001	48.45290858725762
2002	48.798707294552166
2003	49.14450600184673
2004	49.49030470914128
2005	49.836103416435826
2006	50.18190212373038
2007	50.52770083102492
2008	50.873499538319486
2009	51.21929824561404
2010	51.56509695290858
2011	51.91615881809788
2012	52.267220683287164
2013	52.61828254847646
2014	52.969344413665745
2015	53.32040627885504
2016	53.6786703601108
2017	54.03785780240074
2018	54.397045244690666
2019	54.75530932594644
2020	55.11449676823638
2021	55.47306555863343