Year	% of land area
1961	3.2854486947692148
1962	3.26901231997604
1963	3.2617072645124057
1964	3.195961765339703
1965	3.18865670987607
1966	3.1977880292056113
1967	3.1776991266806194
1968	3.1484789048260846
1969	3.104648572044283
1970	3.075428350189749
1971	2.9841151568943287
1972	2.9311535047829853
1973	2.9311535047829853
1974	2.9384585602466187
1975	2.9603737266375196
1976	2.9329797686488934
1977	2.8690605333420995
1978	2.9621999905034277
1979	2.777747340046679
1980	2.5567694122717626
1981	2.5385067736126787
1982	2.5056340240263273
1983	2.4800663299036096
1984	2.439888524853625
1985	2.408842039133182
1986	2.381448081144556
1987	2.3595329147536552
1988	2.2609146659946013
1989	2.2245720150630244
1990	2.2074051347234853
1991	2.2024742222855327
1992	2.199917452873261
1993	2.183846330853267
1994	2.169784099085772
1995	2.1453121632826
1996	2.1237622496648805
1997	2.101664456887389
1998	2.0892458625992116
1999	2.089063236212621
2000	2.083215387340727
2001	2.0722578241566785
2002	2.06056975676036
2003	2.036990729501868
2004	2.0286101974735513
2005	2.0282819870807973
2006	2.002713872710969
2007	1.9579696725637696
2008	1.919982759785739
2009	1.8759690771919635
2010	1.846565745666661
2011	1.8394431995207805
2012	1.8332338003166793
2013	1.8199018549666977
2014	1.8175276729180707
2015	1.8012736573543944
2016	1.8119026877567084
2017	1.8252127175800874
2018	1.8368863880837978
2019	1.845311081768656
2020	1.8518254720513116
2021	1.8518254720513116