Year including construction (constant 2010 US$) 1991 18207.9216372379 1992 17173.3851843278 1993 17700.8338780342 1994 18949.522101586 1995 19065.8652376252 1996 18581.3017757283 1997 19007.0569439054 1998 18402.0952500082 1999 18001.5835400657 2000 18422.9911858743 2001 17859.0794146712 2002 18529.7627287546 2003 20041.8282433021 2004 19034.1282389397 2005 21420.8865969662 2006 20229.9199164349 2007 19195.0971997068 2008 20485.2086737816 2009 19754.4629494214 2010 20215.9371527161 2011 21452.6652257723 2012 21255.2366387842 2013 22357.1320903149 2014 22961.8982202694 2015 23020.8598487398 2016 24145.3325257176 2017 24304.083872706 2018 24227.542158016