Year US Dollars adjusted for inflation) 1991 167912.75 1992 167480.672 1993 175056.609 1994 182063.984 1995 187990.266 1996 187123.656 1997 193041.047 1998 201835.172 1999 211972.844 2000 221348.297 2001 225871 2002 229940.516 2003 237113.031 2004 242498.844 2005 241837.375 2006 247950.344 2007 262488.969 2008 255402.562 2009 228934.719 2010 233438.781 2011 234980.266 2012 223965.281 2013 227549.766 2014 231682.641 2015 236561.562 2016 247558.375 2017 251293.016 2018 257574.75 2019 263704.281 2020 270070.719 2021 276514.938 2022 282610.312