Year	% of land area
1961	43.92582473183566
1962	43.85245901639344
1963	43.49321999595224
1964	43.27059299736896
1965	43.04796599878567
1966	42.89870471564461
1967	42.72414490993726
1968	42.655838899008295
1969	42.68872697834446
1970	42.347196923699656
1971	42.132159481886255
1972	42.06638332321393
1973	41.83616676786075
1974	41.67931592794981
1975	41.58571139445456
1976	41.555353167375024
1977	41.524994940295485
1978	41.61353976927747
1979	41.96263171755415
1980	41.82672796557237
1981	41.7162158846064
1982	41.59355061169464
1983	41.47124963096443
1984	41.34850067507758
1985	41.21171184503883
1986	41.104094593962145
1987	40.98243240474153
1988	40.86112993689967
1989	40.74018718825253
1990	40.60359070632977
1991	40.499375780274654
1992	40.37950458683569
1993	40.25998804437495
1994	40.14082362098873
1995	40.02201384428456
1996	39.928465201295246
1997	39.85151049136068
1998	39.7749239557872
1999	39.69376442132535
2000	39.61727304011243
2001	39.5407713506987
2002	39.465603458442835
2003	39.389477968792285
2004	39.31192412380834
2005	39.234877637662535
2006	39.159052182210125
2007	39.08307777650119
2008	38.999110248911144
2009	38.91545146326511
2010	38.832838878628614
2011	38.750211135043266
2012	38.66765583381344
2013	38.585375856321875
2014	38.502806407833155
2015	38.42056854642456
2016	38.338660726511485
2017	38.259884995126505
2018	38.18240515033929
2019	38.10503413977808
2020	38.02710630294437
2021	37.94969226489846