Year including construction (constant 2010 US$) 1991 5259.63565411606 1992 5380.21471367506 1993 5571.24252592124 1994 5247.16051528587 1995 4352.79267242954 1996 3724.51394259199 1997 3835.95234509424 1998 3529.34451773014 1999 4117.52656710602 2000 3456.01657015019 2001 3177.8815007205 2002 2884.19178463758 2003 2804.51288900546 2004 2519.25992187473 2005 2298.20955191869 2006 2104.03700678146 2007 2014.9605712057 2008 1728.04359613005 2009 1688.35511553616 2010 1615.27050606886 2011 1629.52840925409 2012 1343.32458159767 2013 1203.34630324723 2014 1236.0079837018 2015 1254.69474327067 2016 1233.86907527603 2017 1273.44181686715 2018 1292.39378521903