Year including construction (constant 2010 US$) 1991 21784.0738114172 1992 21494.4337470646 1993 20923.0019466379 1994 21653.7004061882 1995 20090.2456853544 1996 20337.071467273 1997 21294.975820261 1998 21108.0492817233 1999 21797.2462930333 2000 23179.3188665264 2001 23044.0681922718 2002 24000.3322098513 2003 27430.1599493369 2004 27441.2005725762 2005 28969.9512466025 2006 31309.3104113513 2007 30667.8919761904 2008 31571.9544549421 2009 30997.4219006886 2010 32027.9552864194 2011 32394.2682776149 2012 31818.4968390625 2013 31990.3483064619 2014 31497.824938927 2015 30594.7876080212 2016 28936.5476229332 2017 29028.6377668982 2018 31859.4672235629