Year	% of land area
1992	3.7288054123556487
1993	3.731208767439345
1994	3.7095785716860736
1995	3.7191919920208614
1996	3.159210257519497
1997	3.13397502914068
1998	3.0087132335242863
1999	2.864397557584185
2000	2.8666545608619334
2001	2.74805094184301
2002	2.734270982110436
2003	2.7319363112810335
2004	2.694987420166441
2005	2.6796515848052262
2006	2.675556953906846
2007	2.719384235558944
2008	2.7533372868432835
2009	2.748662583815449
2010	2.75116144018583
2011	2.7486752643422294
2012	2.7934380217280843
2013	2.786145489299411
2014	2.8247220642851096
2015	2.8670626519724665
2016	2.9152050320551592
2017	2.9856524158621855
2018	3.0851501439736735
2019	3.1492728724562635
2020	3.2996152263872416
2021	3.3163944343617664