Year	% of land area
1990	2.2108086011703
1991	2.2142168039111794
1992	2.2176250066520593
1993	2.221033209392939
1994	2.2244414121338187
1995	2.227849626443497
1996	2.2312578291843765
1997	2.2346660319252565
1998	2.238074234666136
1999	2.241482437407016
2000	2.2448906401478954
2001	2.267639525494161
2002	2.290388410840427
2003	2.3131881417208966
2004	2.3359429320443836
2005	2.3586923700763442
2006	2.3814252775692144
2007	2.4041717763020896
2008	2.426921030102501
2009	2.4503818295647988
2010	2.4731405532513704
2011	2.474800492519627
2012	2.476460431787883
2013	2.4781754334639348
2014	2.479835409615086
2015	2.4814950985923185
2016	2.4842597964214925
2017	2.4871552175497627
2018	2.488961854369091
2019	2.4933736490634515
2020	2.496967229166761
2021	2.501107523838289