Year	% of land area
1992	26.3033734371314
1993	25.147440434064638
1994	22.38735550837462
1995	20.618070299598962
1996	20.853974994102384
1997	20.94833687190375
1998	20.924746402453408
1999	20.26421325784383
2000	19.886765746638357
2001	15.970747817881575
2002	14.475112054729887
2003	12.856805850436423
2004	12.250530785562633
2005	13.960839820712431
2006	13.189431469686246
2007	14.137768341589998
2008	14.102382637414484
2009	14.069355980184007
2010	15.21585279547063
2011	14.91861288039632
2012	14.63788629393725
2013	14.676788589832068
2014	15.044858523119393
2015	15.527950310559005
2016	16.011042097998622
2017	15.883040935672515
2018	15.976608187134502
2019	16.140350877192983
2020	16.23391812865497
2021	16.374269005847953