Year	% of land area
1961	34.638786634565584
1962	34.695535063011256
1963	34.781897970173006
1964	34.842443126659205
1965	34.90141896888865
1966	34.93538702909119
1967	34.9715825030775
1968	35.0529843522663
1969	35.11104897976602
1970	35.130589473414574
1971	35.2499586030086
1972	35.31161746638668
1973	35.33648350390008
1974	35.35704875062084
1975	35.44286743341873
1976	35.49186922254738
1977	35.556681110408945
1978	35.63566792828561
1979	35.67096560246899
1980	35.71309761040634
1981	35.79588128318103
1982	35.83624143056178
1983	35.89659834200965
1984	35.957645020493146
1985	36.148341637561245
1986	36.38394238682752
1987	36.48447635625049
1988	36.70180158233675
1989	36.83777285907882
1990	36.90231213782118
1991	37.01003684417368
1992	37.17536541311224
1993	36.534554260119286
1994	36.75942661112323
1995	36.9803405687719
1996	37.179043720075406
1997	37.3772026352603
1998	37.471268090305
1999	37.66701620006611
2000	37.80895061461209
2001	37.987661239138525
2002	38.1033987774431
2003	38.36925015305122
2004	38.15921146798536
2005	38.592560294471845
2006	38.74805338969658
2007	38.94337502438997
2008	39.05448607009066
2009	39.289775751072355
2010	39.49958643099233
2011	39.66955611398396
2012	39.550140036560286
2013	39.779079261216765
2014	39.89726749388306
2015	40.04446596321869
2016	40.157790632459275
2017	40.266297696307866
2018	40.444243865184134
2019	40.51576791936059
2020	40.597145244436994
2021	40.65161628548383