Year	% of land area
1961	25.25366403607666
1962	24.01352874859076
1963	23.900789177001126
1964	21.53325817361894
1965	24.23900789177001
1966	21.08229988726043
1967	19.165727170236753
1968	18.489289740698986
1969	18.714768883878243
1970	17.13641488162345
1971	14.656144306651633
1972	12.965050732807216
1973	10.710259301014656
1974	10.710259301014656
1975	10.597519729425029
1976	10.597519729425029
1977	10.822998872604284
1978	11.048478015783541
1979	10.935738444193912
1980	8.342728297632469
1981	7.666290868094701
1982	7.5535512965050735
1983	7.215332581736189
1984	7.440811724915446
1985	7.1025930101465615
1986	7.215332581736189
1987	7.1025930101465615
1988	8.680947012401354
1989	7.891770011273957
1990	7.328072153325817
1991	6.200676437429538
1992	5.862457722660654
1993	3.6076662908680945
1994	3.720405862457723
1995	3.720405862457723
1996	3.720405862457723
1997	4.1713641488162345
1998	5.80608793686584
1999	6.155580608793686
2000	6.730552423900789
2001	7.316798196166855
2002	7.666290868094701
2003	6.899661781285231
2004	6.245772266065389
2005	5.704622322435174
2006	4.937993235625704
2007	4.160090191657272
2008	4.6223224351747465
2009	5.08455467869222
2010	5.546786922209695
2011	5.896279594137542
2012	6.211950394588501
2013	6.110484780157836
2014	6.00901916572717
2015	5.907553551296505
2016	5.80608793686584
2017	5.704622322435174
2018	5.659526493799324
2019	5.659526493799324
2020	5.659526493799324
2021	5.659526493799324