Year	% of land area
1990	37.14149342384387
1991	36.69601187950785
1992	36.250530335171824
1993	35.805048790835805
1994	35.35956724649979
1995	34.91408570216377
1996	34.46860415782775
1997	34.02312261349172
1998	33.5776410691557
1999	33.132159524819684
2000	32.686677980483665
2001	32.241196436147646
2002	31.795714891811627
2003	31.350233347475605
2004	30.904751803139586
2005	30.45927025880356
2006	30.013788714467545
2007	29.568307170131526
2008	29.1228256257955
2009	28.677344081459484
2010	28.231862537123465
2011	27.78638099278744
2012	27.340899448451424
2013	26.895417904115398
2014	26.44993635977938
2015	26.004454815443363
2016	25.558973271107337
2017	25.11349172677132
2018	24.6680101824353
2019	24.222528638099277
2020	23.777047093763258
2021	23.33156554942724