Year	% of land area
1990	65.44957047406935
1991	65.90227414330218
1992	65.99006230529595
1993	66.07785046728972
1994	66.16563862928349
1995	66.25342679127726
1996	66.34121495327103
1997	66.42900311526479
1998	66.51679127725856
1999	66.60457943925233
2000	66.6923676012461
2001	66.77940809968847
2002	66.86644859813084
2003	66.95348909657322
2004	67.04052959501557
2005	67.12757009345795
2006	67.21461059190031
2007	67.30165109034267
2008	67.38869158878505
2009	67.47573208722741
2010	67.56277258566978
2011	67.64959501557632
2012	67.73641744548287
2013	67.8232398753894
2014	67.91006230529595
2015	67.99688473520249
2016	68.08395638629284
2017	68.22400623538581
2018	68.31114575214342
2019	68.39812938425565
2020	68.48511301636789
2021	68.57209664848013