Year US Dollars adjusted for inflation) 1991 734.797 1992 738.408 1993 688.64 1994 659.261 1995 604.591 1996 555.09 1997 545.725 1998 570.495 1999 559.725 2000 547.379 2001 541.092 2002 545.095 2003 517.887 2004 521.861 2005 506.474 2006 514.524 2007 519.913 2008 527.282 2009 527.346 2010 529.833 2011 538.731 2012 546.93 2013 558.39 2014 570.41 2015 530.394 2016 510.221 2017 493.449 2018 478.387 2019 484.953 2020 493.847 2021 503.646 2022 515.924