Year % of land area 1961 1.0555378814133056 1962 1.105323382170178 1963 1.0671434453385518 1964 1.0931967521095125 1965 1.0920125108926506 1966 1.0907809000271145 1967 1.0838175616719667 1968 1.1075023860092037 1969 1.1266870937223656 1970 1.145208626354085 1971 1.1656723145814578 1972 1.1795989912917533 1973 1.2068879108181931 1974 1.2301488163163141 1975 1.2540244317099307 1976 1.2656774370436912 1977 1.3000206438200181 1978 1.3077893140425252 1979 1.3309532148889027 1980 1.3626437050038858 1981 1.3865181549559806 1982 1.4022449751625192 1983 1.3390930536809882 1984 1.3651325679248094 1985 1.3940408422124415 1986 1.419021121978548 1987 1.4533579729644686 1988 1.4829282688006724 1989 1.4979649849072316 1990 1.5195159930517366 1991 1.5513130929623817 1992 1.5643262963519131 1993 1.6093711862184943 1994 1.6372764044995953 1995 1.6706772896071083 1996 1.7108208222194918 1997 1.7339307363668222 1998 1.7611973823363847 1999 1.80154118282435 2000 1.8323245263883643 2001 1.876549846616517 2002 1.9005359489438065 2003 1.9434739394878628 2004 2.001234006616155 2005 2.073174200995956 2006 2.117202376774124 2007 2.166211541381829 2008 2.2090135038158962 2009 2.24503016885443 2010 2.3212389054669256 2011 2.3482078974777267 2012 2.3811474525903082 2013 2.4248762977219904 2014 2.4491652700543813 2015 2.5203056287065144 2016 2.52177183849358 2017 2.545308041039486 2018 2.6122781096689622 2019 2.6392898247197776 2020 2.64850784100462 2021 2.680058014520537