Year	% of land area
1990	13.285999999999998
1991	13.386400000000002
1992	13.486800000000002
1993	13.5872
1994	13.6876
1995	13.788
1996	13.888399999999997
1997	13.988800000000001
1998	14.089200000000002
1999	14.189599999999999
2000	14.29
2001	14.327225000000002
2002	14.364449999999998
2003	14.401675
2004	14.438900000000002
2005	14.476125000000001
2006	14.513349999999999
2007	14.550574999999998
2008	14.587800000000001
2009	14.625024999999999
2010	14.662249999999998
2011	14.8532
2012	15.04415
2013	15.2351
2014	15.42605
2015	15.617
2016	15.6165
2017	15.64
2018	15.664
2019	15.687499999999998
2020	15.711
2021	15.7345