Year including construction (constant 2010 US$) 1991 17148.6644849854 1992 14404.8008821672 1993 13257.9562342226 1994 11595.9760567968 1995 12226.8376794186 1996 12077.2242791729 1997 12997.5174638416 1998 13345.3828975312 1999 13693.5361056605 2000 14673.4064351569 2001 14885.4352703686 2002 15392.2044200905 2003 16499.1357967474 2004 17972.4537000726 2005 18662.8943341968 2006 19910.7998555607 2007 20734.0481846944 2008 21147.1507867609 2009 20542.8067829425 2010 21536.8623264195 2011 22990.5911494698 2012 23140.1899532087 2013 23620.1560720695 2014 23443.0128515372 2015 23890.8977825067 2016 24335.4253512187 2017 24245.0504298993 2018 24801.2772250484