Year thousand metric tons of CO2 equivalent 1990 54.1 1991 50.3 1992 51.8 1993 53.1 1994 53.7 1995 58.5 1996 64 1997 66.6 1998 68.6 1999 70.6 2000 71.2 2001 68.6 2002 73.2 2003 73.4 2004 73.5 2005 73.5 2006 76.6 2007 75.6 2008 68.4 2009 62.7 2010 59.8 2011 61 2012 58.9 2013 62 2014 62.5 2015 61.4 2016 66.3 2017 65.4 2018 72.9 2019 76.7 2020 50.9