Year	% of land area
1961	0.6738856452069241
1962	0.6893181408986857
1963	0.6944623061292728
1964	0.7047506365904472
1965	0.7098948018210345
1966	0.7176110496669154
1967	0.7253272975127961
1968	0.7304714627433834
1969	0.7407597932045578
1970	0.7459039584351449
1971	0.7664806193574938
1972	0.784485197664549
1973	0.8071195246791327
1974	0.8127781064327787
1975	0.8153501890480722
1976	0.8179222716633658
1977	0.8354124334473624
1978	0.8487872630468891
1979	0.8642197587386506
1980	0.9305794902132257
1981	1.066385452300728
1982	1.0314051287327348
1983	1.0391213765786156
1984	1.0355204609172046
1985	1.0632989531623755
1986	1.0910774454075465
1987	1.1502353455592993
1988	1.1203991872218937
1989	1.0931351114997814
1990	1.0689575349160214
1991	1.169268756912472
1992	1.1975616656807015
1993	1.178528254327529
1994	1.2027058309112888
1995	1.23048432315646
1996	1.2345996553409295
1997	1.2330564057717535
1998	1.2428303197098691
1999	1.232027572725636
2000	1.2721520615242161
2001	1.2819259754623318
2002	1.2983873042002108
2003	1.0910774454075465
2004	1.349828956506083
2005	1.3410838756140848
2006	1.3400550425679674
2007	1.3508577895522005
2008	1.3642326191517273
2009	1.351372206075259
2010	1.3637182026286685
2011	1.37915069832043
2012	1.3673191182900795
2013	1.3025026363846808
2014	1.3770930322281951
2015	1.3863525296432522
2016	1.3503433730291416
2017	1.3729777000437255
2018	1.3925255279199567
2019	1.4038426914272488
2020	1.4393374315183003
2021	1.4480825124102985