Year thousand metric tons of CO2 equivalent 1990 4.27 1991 4.885 1992 4.9225 1993 4.77 1994 4.8475 1995 4.8475 1996 4.85 1997 4.925 1998 4.925 1999 5.0025 2000 5.0025 2001 5.0025 2002 5.1175 2003 5.1175 2004 5.1175 2005 5.1175 2006 5.1175 2007 5.1575 2008 5.2025 2009 5.2425 2010 5.2525 2011 5.275 2012 5.3 2013 5.325 2014 5.365 2015 5.405 2016 5.4225 2017 5.45 2018 5.4675 2019 5.4925 2020 5.5175