Year including construction (constant 2015 US$) 1991 30581.168578007302 1992 23867.341741450316 1993 20305.522470099055 1994 16556.509754090228 1995 15248.30335718825 1996 15530.087760847904 1997 16556.400073787572 1998 16849.72697441034 1999 17666.87654434887 2000 20146.4397722692 2001 22494.439835781806 2002 24740.711973224716 2003 25476.414883279034 2004 27113.456910470715 2005 28621.40846398343 2006 30994.904665641527 2007 31682.94325851201 2008 31355.87814918608 2009 31764.02846005037 2010 33379.13533783591 2011 33669.40233542705 2012 33308.475581593404 2013 33339.844995428204 2014 33351.25481700296 2015 32269.59331102851 2016 32395.8845312947 2017 34150.30968266353 2018 35172.19475958991 2019 37221.184869330216 2020 38187.12475865126 2021 38867.6742518233 2022 39801.10114281333