Year current US$ 1971 175.39585800779858 1972 191.1588378946918 1973 238.33076299411368 1974 290.1749548442536 1975 311.76500805802243 1976 326.66817112194093 1977 335.4993371701514 1978 368.8477376178389 1979 402.63387265452405 1980 525.6617680323479 1981 812.3397873859647 1982 722.6337820420123 1983 605.8569403659175 1984 511.56980122572463 1985 451.1522965384995 1986 449.0298171219492 1987 489.2247580363219 1988 501.5365322662411 1989 472.8525032444208 1990 519.2415667287029 1991 531.305838648704 1992 513.8656637643022 1993 465.90355777245884 1994 441.4084872706663 1995 502.7500850923888 1996 509.401431881479 1997 518.1415216977575 1998 494.5556197139952 1999 492.8482577934953 2000 486.31044804784017 2001 455.1672031819631 2002 485.90062496828403 2003 598.9944002214252 2004 722.5667427748433 2005 819.6849624714264 2006 957.529903808965 2007 1046.9606488101174 2008 1115.0720535145203 2009 1115.7266911046868 2010 1252.220184589158 2011 1353.1478019487797 2012 1399.1466563291162 2013 1469.0864872033587 2014 1543.0931452568218 2015 1378.5229004845673 2016 1259.5367368638751 2017 1312.1216043273814 2018 1318.3224409878105 2019 1312.761249569783 2020 1227.9943382199815 2021 1305.2666591415914