Year	% of land area
1961	1.7422364531025598
1962	1.917132776580037
1963	1.5404330029362403
1964	1.4751832207157969
1965	1.4186782546692274
1966	1.3890804153115004
1967	1.3487197252782366
1968	1.5135258762473975
1969	1.5135258762473975
1970	1.5135258762473975
1971	1.6144276013305574
1972	1.6144276013305574
1973	1.681695418052664
1974	1.681695418052664
1975	1.681695418052664
1976	1.681695418052664
1977	1.681695418052664
1978	1.681695418052664
1979	1.681695418052664
1980	1.7825971431358236
1981	1.8498649598579302
1982	1.8498649598579302
1983	1.9507666849410903
1984	1.9507666849410903
1985	1.9507666849410903
1986	2.018034501663197
1987	2.186204043468463
1988	2.186204043468463
1989	2.186204043468463
1990	2.236654906010043
1991	2.3543735852737298
1992	2.4552753103568894
1993	2.5898109438011025
1994	2.623444852162156
1995	2.6907126688842626
1996	2.858882210689529
1997	2.858882210689529
1998	2.8992429007227924
1999	3.077502615036375
2000	3.0943195692169017
2001	3.1952212943000617
2002	3.228855202661115
2003	3.363390836105328
2004	3.43402204366354
2005	3.44074882533575
2006	3.632462102993754
2007	3.7602709547657565
2008	3.834265553160074
2009	3.968801186604287
2010	4.111745297138763
2011	4.167241245934501
2012	4.30514027021482
2013	4.372408086936926
2014	4.372408086936926
2015	4.372408086936926
2016	4.372408086936926
2017	4.372408086936926
2018	4.473309812020086
2019	4.473309812020086
2020	4.574211537103246
2021	4.574211537103246