Year	% of land area
1990	36.0477774855482
1991	36.22343627510769
1992	36.80553033049287
1993	36.95220716235489
1994	37.11877883226546
1995	37.286005872351666
1996	37.45210117211424
1997	37.61989784271497
1998	37.78722531169184
1999	37.954460342123184
2000	37.9864567368048
2001	38.11200198871347
2002	38.24389862526875
2003	38.359812175191756
2004	38.482844636722604
2005	38.606183045219275
2006	38.73312752498318
2007	38.85417836031757
2008	38.98019846607116
2009	39.091680543012544
2010	39.199560603771694
2011	39.28276134058227
2012	39.36356286023831
2013	39.43211266927332
2014	39.50696951818414
2015	39.595374339952464
2016	39.64469080414316
2017	39.70558969488267
2018	39.75099735476558
2019	39.79785175767905
2020	39.84321414990739
2021	39.88750697835715