Year	% of land area
1990	43.31809365475201
1991	43.04479080077584
1992	42.77148794679967
1993	42.49818509282349
1994	42.22488223884732
1995	41.95157938487116
1996	41.67827653089498
1997	41.404973676918814
1998	41.131670822942645
1999	40.858367968966476
2000	40.5850651149903
2001	40.31176226101413
2002	40.038459407037955
2003	39.76515655306179
2004	39.491853699085624
2005	39.21855084510945
2006	38.94524799113328
2007	38.6719451371571
2008	38.39864228318093
2009	38.125339429204764
2010	37.852036575228595
2011	37.57874757550568
2012	37.305458575782765
2013	37.03216957605985
2014	36.758880576336935
2015	36.48559157661402
2016	36.21224715987808
2017	35.93890274314215
2018	35.66555832640621
2019	35.39221390967027
2020	35.11886949293433
2021	34.84552507619839