Year including construction (constant 2015 US$) 1991 19360.2375633426 1992 19221.2394438869 1993 19585.99701643582 1994 20382.63654610224 1995 19876.686599271557 1996 20683.48271993455 1997 21210.435856041026 1998 20908.053179553277 1999 20676.3505831193 2000 20928.24950671289 2001 20585.243353890175 2002 20127.415300363766 2003 20270.11729903132 2004 20852.905140605788 2005 20997.785328779228 2006 21364.067162128336 2007 21499.234129220375 2008 21417.19500037027 2009 20660.048894283093 2010 21772.736579427197 2011 22429.47772441443 2012 21817.22395316027 2013 22072.413801386 2014 21601.15861845754 2015 21459.405543812238 2016 21672.85860167745 2017 21726.278764759878 2018 21512.37203000242 2019 20978.548412296437 2020 21071.513655636267 2021 20885.030194991785 2022 20555.586237108877