Year	% of land area
1961	39.04176403026667
1962	39.010306233160534
1963	39.020972071116766
1964	39.04344078128143
1965	39.06812093288861
1966	39.06661203262382
1967	39.137798678662335
1968	39.911267378388814
1969	39.801801593259086
1970	39.129120723280415
1971	39.21680658136759
1972	39.20079914641024
1973	39.086876111655606
1974	39.11321649675893
1975	39.092102869460945
1976	39.13213693196141
1977	38.809644195406456
1978	38.8799591346118
1979	38.75436917898012
1980	38.812765084909316
1981	38.80551110877235
1982	38.728349702951085
1983	38.4578270385685
1984	38.532119266104004
1985	38.523144183111555
1986	37.91220408599664
1987	37.848412651556224
1988	37.868407140040986
1989	37.700108612996196
1990	37.58756558646155
1991	37.46047593865282
1992	38.22545713911389
1993	37.95708222454391
1994	38.16600623464296
1995	37.91658073947152
1996	37.835596184365755
1997	37.670360066447145
1998	37.679516675789415
1999	37.306600535283955
2000	37.30133377597632
2001	37.27809268588701
2002	36.91718403366295
2003	36.62470020655903
2004	35.18673791503173
2005	35.66287058970979
2006	35.55855202101403
2007	35.14364951641396
2008	34.795908731208954
2009	34.508798645204145
2010	34.13706155048604
2011	34.643878921746335
2012	34.27478885312368
2013	33.79614086859852
2014	33.842043440991986
2015	32.99709851615284
2016	32.80842106952009
2017	33.75566099495967
2018	33.305528469740224
2019	33.44143550698976
2020	33.15214430475057
2021	33.581566465414504