Year % of land area 1992 46.467117570873505 1993 45.013671031803135 1994 44.56756367822708 1995 43.86242624838106 1996 43.675348971074975 1997 43.70413009066053 1998 43.81925456900274 1999 43.15728881853504 2000 43.171679378327816 2001 43.21485105770614 2002 43.22924161749892 2003 43.258022737084474 2004 35.86127500359764 2005 36.26421067779537 2006 36.235429558209816 2007 36.221038998417036 2008 36.17786731903871 2009 35.94761836235429 2010 35.40077709022881 2011 35.14750323787595 2012 35.04101309540941 2013 35.77637070082026 2014 34.767592459346666 2015 34.797812634911494 2016 34.451000143905596 2017 34.31860699381206 2018 34.166067060008636 2019 34.143042164340194 2020 34.21931213124191 2021 34.24809325082745