Year	% of land area
1961	4.895552578772669
1962	4.922451219315375
1963	4.949349859858083
1964	4.97624850040079
1965	5.003147140943496
1966	5.030045781486204
1967	5.05694442202891
1968	5.083843062571618
1969	5.110741703114324
1970	5.24792476988213
1971	5.315171371238898
1972	5.382417972595665
1973	5.5169111753091995
1974	5.584157776665967
1975	5.584157776665967
1976	5.646024649914193
1977	5.5074966511192525
1978	5.368968652324312
1979	5.23044065352937
1980	5.159159256091197
1981	5.020631257296256
1982	4.8148566571445475
1983	4.74492019173351
1984	4.673638794295337
1985	4.631945901454141
1986	4.51090201901196
1987	4.137010915468332
1988	4.114147071007031
1989	4.12894132330552
1990	3.768499540033247
1991	3.611142492858411
1992	3.281634146210251
1993	3.098723390519843
1994	3.0610652937600533
1995	2.851255897526939
1996	2.669690073863667
1997	2.665655277782261
1998	2.661620481700855
1999	2.4208776488436277
2000	2.3536310474868603
2001	2.3536310474868603
2002	2.219137844773325
2003	2.017398040703023
2004	2.017398040703023
2005	1.9501514393462556
2006	1.8156582366327205
2007	1.69730421824481
2008	1.7026745318291614
2009	1.7080448454135126
2010	1.7120702269707289
2011	1.7174391956230532
2012	1.7228095092074045
2013	1.728179822791756
2014	1.7335501363761077
2015	1.7375755179333234
2016	1.7429458315176751
2017	1.7483161451020266
2018	1.7536851137543508
2019	1.757710495311567
2020	1.7630808088959184
2021	1.7671061904531344