Year	% of land area
1990	27.84050136152491
1991	28.47907055902611
1992	29.117639756527314
1993	29.756208954028512
1994	30.39477815152971
1995	31.033347349030915
1996	31.671916546532113
1997	32.310485744033315
1998	32.94905494153452
1999	33.58762413903572
2000	34.25637274549098
2001	34.58050028083126
2002	34.835307790958645
2003	35.11418641453496
2004	35.40705557113667
2005	35.70425173816346
2006	36.00299811615697
2007	36.28442026807718
2008	36.597951082598236
2009	36.89928809208679
2010	37.089938201235974
2011	37.10192046091061
2012	37.079778493032926
2013	37.082113512324824
2014	37.08444853161672
2015	37.12753246701263
2016	37.14286858140298
2017	37.15223391736539
2018	37.15664678147688
2019	37.16772156446949
2020	37.177305488549756
2021	37.17275210932335