Year	% of land area
1961	44.96350364963504
1962	44.96350364963504
1963	45
1964	44.89051094890511
1965	45.14598540145985
1966	45.25547445255474
1967	45.4014598540146
1968	45.25547445255474
1969	45.07299270072993
1970	44.89051094890511
1971	43.79562043795621
1972	42.846715328467155
1973	41.824817518248175
1974	40.948905109489054
1975	39.416058394160586
1976	39.23357664233576
1977	40.47445255474453
1978	40.65693430656934
1979	40.76642335766423
1980	40.802919708029194
1981	40.729927007299274
1982	40.65693430656934
1983	40.51094890510949
1984	40.620437956204384
1985	40.58394160583942
1986	40.54744525547445
1987	40.54744525547445
1988	40.76642335766423
1989	40.51094890510949
1990	40.912408759124084
1991	41.13138686131387
1992	41.13138686131387
1993	41.09489051094891
1994	41.09489051094891
1995	41.13138686131387
1996	41.27737226277372
1997	41.42335766423358
1998	41.56934306569343
1999	41.78832116788321
2000	41.75182481751825
2001	41.56934306569343
2002	41.605839416058394
2003	40.912408759124084
2004	40.948905109489054
2005	39.306569343065696
2006	40.87591240875913
2007	40.839416058394164
2008	43.1021897810219
2009	43.84306569343065
2010	43.84306569343065
2011	43.832116788321166
2012	43.84306569343065
2013	43.332116788321166
2014	42.85729927007299
2015	42.85766423357664
2016	43.127737226277375
2017	42.85697080291971
2018	42.84967153284672
2019	42.846715328467155
2020	42.53850364963503
2021	41.47189781021898