Year	% of land area
1961	35.52256483284605
1962	35.59132697379148
1963	35.69841964312366
1964	35.77666048306277
1965	35.85377884548947
1966	35.876644128149685
1967	35.90707574070836
1968	35.96008162323884
1969	35.94740178467273
1970	35.98724973636329
1971	36.02023810325579
1972	36.10766662950019
1973	36.17244605393862
1974	36.15849670988055
1975	36.227531021348696
1976	36.27143114488282
1977	36.30029381031455
1978	36.396673276161906
1979	36.4115129067253
1980	36.507925627920756
1981	36.528984786021226
1982	36.652296136484374
1983	36.6168598628195
1984	36.707457371499615
1985	36.91373975534474
1986	37.04832711339005
1987	37.20810688806854
1988	37.37724838207057
1989	37.528675027773765
1990	37.580426681207726
1991	37.703377416640805
1992	38.42309816803737
1993	37.93610158655845
1994	38.19445979947663
1995	38.482892424167964
1996	38.642761751336685
1997	38.83748174667945
1998	38.93446590162202
1999	39.134970312312845
2000	39.24384905831909
2001	39.4324558178978
2002	39.52418108830811
2003	39.77553951581276
2004	39.60319098837013
2005	39.952385287227976
2006	40.10337025935924
2007	40.26207656135797
2008	40.346000965955255
2009	40.53297200994733
2010	40.70315490309838
2011	40.882990705645355
2012	40.918691831042906
2013	41.10763544070091
2014	41.22992991609425
2015	41.35055980913247
2016	41.4759344805158
2017	41.60057937739476
2018	41.73020024921055
2019	41.76992261557939
2020	41.86282055567444
2021	41.8987444834941