Year including construction (constant 2010 US$) 1991 15930.7247245886 1992 15787.3617009842 1993 15981.8008678002 1994 16653.9406771134 1995 16162.3946539527 1996 15515.9589067806 1997 15352.0538165679 1998 14479.6214614208 1999 13332.0433220036 2000 14456.9989471667 2001 15015.1646724402 2002 16185.7258992698 2003 17144.9366256547 2004 19172.060434765 2005 19904.572525318 2006 18836.5616370419 2007 18537.3066998614 2008 19314.4143056027 2009 19486.7063115948 2010 20222.0849214438 2011 22328.8034701184 2012 23580.7331548511 2013 22307.9958983786 2014 21806.5397113174 2015 20803.6796986806 2016 20766.781292645 2017 20033.7212037287 2018 19564.461683712