Year including construction (constant 2010 US$) 1991 32390.4401287742 1992 31922.4555700103 1993 32609.5865828017 1994 30594.6480098952 1995 30077.0691555948 1996 30477.9389698221 1997 28872.754361288 1998 28418.2159710536 1999 27133.734977583 2000 28437.7309348808 2001 26571.6772136099 2002 27433.3508624923 2003 28748.1883390776 2004 27857.5029053943 2005 28211.6245362447 2006 27750.6475145779 2007 28664.4287759145 2008 30145.6467777881 2009 29980.7452322704 2010 31976.0354250259 2011 31499.3016620367 2012 25422.9619064827 2013 23383.5032498134 2014 24336.1119903256 2015 24074.2230598637 2016 29689.3899824443 2017 30056.7557198241