Year	% of land area
2006	29.862794420306425
2007	30.15206951749371
2008	30.441344614681
2009	30.730619711868286
2010	31.01989480905557
2011	31.034827349645553
2012	31.049759890235535
2013	31.06469243082552
2014	31.079624971415505
2015	31.094557512005487
2016	31.101989480905555
2017	31.121198262062656
2018	31.12279899382575
2019	31.125314429453464
2020	32.37780948983232
2021	32.38125817576407