Year	% of land area
1992	39.63102604691322
1993	39.642970211541225
1994	39.65491437616923
1995	39.66685854079724
1996	39.67880270542524
1997	39.690746870053246
1998	39.70269103468125
1999	39.71463519930926
2000	39.72657936393726
2001	39.81551302345661
2002	39.904446682975966
2003	39.99338034249533
2004	40.08231400201468
2005	40.17124766153403
2006	40.26018132105339
2007	40.34911498057274
2008	40.4380486400921
2009	40.52698229961146
2010	40.61591595913081
2011	40.61591595913081
2012	40.61591595913081
2013	40.61591595913081
2014	40.61591595913081
2015	40.61591595913081
2016	40.61591595913081
2017	40.61591595913081
2018	40.61591595913081
2019	40.61591595913081
2020	40.61591595913081
2021	40.61591595913081