Year % of land area 1992 11.440495035256872 1993 11.440495035256872 1994 11.440495035256872 1995 11.095121600230248 1996 11.239027198158007 1997 11.296589437329112 1998 11.397323355878545 1999 11.368542236292992 2000 11.411713915671319 2001 11.440495035256872 2002 11.498057274427975 2003 11.541228953806302 2004 6.504533026334725 2005 6.763563102604691 2006 6.648438624262484 2007 6.662829184055259 2008 6.605266944884155 2009 6.231112390271982 2010 5.684271118146496 2011 5.430997265793639 2012 5.3245071233270975 2013 5.982155705856957 2014 5.252554324363218 2015 5.291408835803713 2016 4.950352568714924 2017 4.662541372859405 2018 4.475464095553317 2019 4.417901856382214 2020 4.461073535760541 2021 4.489854655346093