Year current US$ 1970 185.36022974310768 1971 160.63211529771542 1972 172.15359427395038 1973 171.56994524795604 1974 218.49900777084386 1975 261.59294169882935 1976 307.3931024858851 1977 306.98564255464055 1978 337.7094776862901 1979 344.3441177518148 1980 455.55656766784324 1981 978.9712881564445 1982 876.9136176516009 1983 637.2051418161086 1984 526.7260508287704 1985 504.3595569712417 1986 448.87643965207127 1987 432.7228547015108 1988 440.1131565444003 1989 388.25797716495146 1990 404.2347780730511 1991 408.2423775099914 1992 396.13415882787166 1993 339.15585477209896 1994 337.3123407043571 1995 391.7218390026316 1996 423.027186614025 1997 422.07937927066695 1998 412.40694951019873 1999 424.2475277174871 2000 439.3452373483225 2001 437.02292521265747 2002 478.19859591609315 2003 524.0224215980506 2004 618.6394402536657 2005 712.4426003979098 2006 908.2315355870409 2007 1015.6491404548799 2008 1160.2725420664374 2009 1104.619890029182 2010 1236.8518020373617 2011 1372.4583314895226 2012 1504.4733347481308 2013 1623.47934598446 2014 1769.1077745655004 2015 1678.7103453004393 2016 1604.0932915306792 2017 1528.8647231127131 2018 1611.40148531838 2019 1572.5190211008862 2020 1483.4942211070304 2021 1566.6330120875841