Year	% of land area
1990	33.422625464425636
1991	33.666803971508315
1992	34.75795350201721
1993	35.075932009648106
1994	35.30681784762933
1995	35.537705468927484
1996	35.76859483576221
1997	35.99989415681348
1998	36.23106355085993
1999	36.46237598535999
2000	36.509018546261466
2001	36.66290145910183
2002	36.80296666386817
2003	36.94367095960981
2004	37.09554120149135
2005	37.24411790944995
2006	37.39955050601767
2007	37.54538232485643
2008	37.69963500882937
2009	37.847470295990554
2010	37.97557743438612
2011	38.059867739511596
2012	38.137422082846285
2013	38.19940951659411
2014	38.281500018691744
2015	38.371775631633625
2016	38.425885205730985
2017	38.503769611603474
2018	38.5604198624425
2019	38.61817502366072
2020	38.67521099587901
2021	38.72997120426859