Year	% of land area
1961	2.830984218768823
1962	2.8227705314803253
1963	2.814556844191828
1964	2.7899157823263354
1965	2.7680126162236753
1966	2.75158524164668
1967	2.7378957628325176
1968	2.721468388255522
1969	2.699565222152862
1970	2.6119525577422213
1971	2.5489809551970737
1972	2.4914851441775907
1973	2.4750577696005958
1974	2.466844082312098
1975	2.458630395023601
1976	2.4531546034979357
1977	2.461368290786433
1978	2.4641061865492655
1979	2.6119525577422213
1980	2.562670434011236
1981	2.562670434011236
1982	2.5790978085882315
1983	2.587311495876729
1984	2.6119525577422213
1985	2.620166245030719
1986	2.6530209941847094
1987	2.655758889947542
1988	2.672186264524537
1989	2.713254700967025
1990	2.672186264524537
1991	2.7652747204608428
1992	2.7461094501210153
1993	2.77348840774934
1994	2.820032635717493
1995	3.085608524712247
1996	3.0992980035264095
1997	2.8419358018201533
1998	2.866576863685646
1999	2.8419358018201533
2000	2.852887384871483
2001	2.866576863685646
2002	2.8638389679228133
2003	2.847411593345818
2004	2.847411593345818
2005	2.836460010294488
2006	2.8337221145316556
2007	2.825508427243158
2008	2.8057955777507635
2009	2.7769381564105093
2010	2.7540493478332295
2011	2.735157867069685
2012	2.718182913340123
2013	2.7035900453918322
2014	2.702652365875303
2015	2.7000413756429174
2016	2.69388608214041
2017	2.6980277878961334
2018	2.7013376863832073
2019	2.695892016850455
2020	2.706567659936588
2021	2.704038213413128