Year	% of land area
1961	10.928554309908662
1962	10.896599472745187
1963	10.875296247969537
1964	10.853993023193887
1965	10.827363992224322
1966	10.77943173647911
1967	10.72830399701755
1968	10.677176257555987
1969	10.626048518094427
1970	10.574920778632865
1971	10.529118845365216
1972	10.48012142838122
1973	10.430058850158442
1974	10.487577557052699
1975	10.33099885495167
1976	10.311115841610523
1977	10.291232838920992
1978	10.271349825579847
1979	10.257449471413734
1980	10.244188213990894
1981	10.309695630176018
1982	10.832689798418235
1983	11.429180092136447
1984	12.142838122120736
1985	12.792586477778073
1986	12.835192927329375
1987	12.8032380901659
1988	12.877799376880676
1989	13.016270337922403
1990	13.186696136127606
1991	13.301200969296728
1992	13.090831624637179
1993	12.920405826431978
1994	12.856496152105024
1995	12.737211660545533
1996	12.711554787217613
1997	12.679626511067582
1998	12.679653140155281
1999	12.679679769242977
2000	12.679719904305609
2001	12.742981982665032
2002	12.784934293993238
2003	12.805582611054392
2004	12.826230531104828
2005	12.852204953450242
2006	12.888830634981227
2007	12.882849956884224
2008	12.908823436303752
2009	12.929470801199505
2010	12.796080105144632
2011	12.641386095817403
2012	12.497343743126352
2013	12.39590801698002
2014	12.313645272778807
2015	12.235643191232068
2016	12.0845010177659
2017	11.933357551652552
2018	11.782214074887545
2019	11.627562655713922
2020	11.606259340172407
2021	11.59560768240165