Year including construction (constant 2010 US$) 1991 26468.6603254437 1992 26347.9730268216 1993 27028.4206194162 1994 28163.5979171068 1995 28284.2552687315 1996 28879.7231043611 1997 29018.1879762825 1998 28293.5753606719 1999 27762.0870527625 2000 28057.4344243293 2001 27776.5092059935 2002 27029.3685248939 2003 26855.8057173821 2004 27769.638727572 2005 27468.0600919878 2006 27639.171415057 2007 27725.6125021568 2008 27661.9778576625 2009 26920.6080558081 2010 27919.8071744233 2011 28681.4676056493 2012 27938.9283467484 2013 28204.5669370061 2014 27336.244571665 2015 24705.2354423218 2016 24784.2368421124 2017 24571.1642319595 2018 24424.6132949319