Year	% of land area
1990	26.08850655666231
1991	25.93102927859946
1992	25.773552000536608
1993	25.61607472247375
1994	25.458597444410902
1995	25.301120166348056
1996	25.143642888285207
1997	24.986165610222354
1998	24.828688332159505
1999	24.671211054096652
2000	24.51373377603381
2001	24.356259851762417
2002	24.19878592749103
2003	24.041312003219637
2004	23.88383807894825
2005	23.726364154676858
2006	23.568890230405472
2007	23.411416306134086
2008	23.253942381862696
2009	23.09646845759131
2010	22.938994533319917
2011	23.05599490223698
2012	23.17299527115404
2013	23.2899956400711
2014	23.40699600898816
2015	23.52399637790522
2016	23.641010161988127
2017	23.758023946071035
2018	23.87500419223933
2019	23.992017976322234
2020	24.109031760405138
2021	24.226045544488045