Year	% of land area
1961	0.23895847735068212
1962	0.24131856107760244
1963	0.24397365527038778
1964	0.24847256487482963
1965	0.24839881225836338
1966	0.2500213698206211
1967	0.25230770093107513
1968	0.2545940320415292
1969	0.26484564573033936
1970	0.2799649321059226
1971	0.2849801100256283
1972	0.29589549726263475
1973	0.30474671027327566
1974	0.30813934063933823
1975	0.3095406444861902
1976	0.31603089388213607
1977	0.31698968072471895
1978	0.3213609374100755
1979	0.32187676556001144
1980	0.3208451092601396
1981	0.3290246699234091
1982	0.34133085578616595
1983	0.35592142345578187
1984	0.36837498878994895
1985	0.37242792425373117
1986	0.3764808597175133
1987	0.38340769487379567
1988	0.39247198549980494
1989	0.4038789155115188
1990	0.41646333507282884
1991	0.4216682605499165
1992	0.4284266657928913
1993	0.4244594120926742
1994	0.43246738715422356
1995	0.4420255298653022
1996	0.45326608201591734
1997	0.4554701118493713
1998	0.46017204216073976
1999	0.46964937044459176
2000	0.47603297551888557
2001	0.47959542240635833
2002	0.49624980650454753
2003	0.5021772061950808
2004	0.5106918612344018
2005	0.551509923665356
2006	0.5589637912174661
2007	0.5701514422064969
2008	0.5697609074667955
2009	0.5566422273889653
2010	0.5873145679093629
2011	0.6015360029533771
2012	0.627535001405636
2013	0.652417030955513
2014	0.65951962212187
2015	0.6609870991459276
2016	0.6767604575357224
2017	0.6756664043363131
2018	0.6709600559611032
2019	0.6684530810323602
2020	0.6491034078037493
2021	0.6782934148077193