Year current US$ 1960 5.517664415860121 1961 5.370486432173365 1962 7.885703716037806 1963 9.848545491171262 1964 10.094833660046927 1965 9.622768879810272 1966 7.065115141147288 1967 8.878305451636471 1968 6.960566459290672 1969 5.685301113022973 1970 7.097719638400091 1971 6.998169174000412 1972 4.874934115864156 1973 4.39211737453954 1974 7.082779664453109 1975 10.730987979144935 1976 14.3560691952515 1977 8.188557228095418 1978 8.445990663509836 1979 9.073816459898978 1980 14.390493531020525 1981 9.520684399909163 1982 9.899098498071838 1983 7.277528761690488 1984 6.6450454973786455 1985 6.878699872137741 1986 8.03102632826581 1987 6.399548953837165 1988 10.789786780502913 1989 10.687882994612824 1990 7.872437344319513 1991 9.588890994504368 1992 6.91913170128029 1993 6.579707446183188 1994 9.185490942997399 1995 3.760888725447574 1996 5.007840211969543 1997 4.827203648237288 1998 5.674814995343421 1999 4.099216475241502 2000 3.560408536038328 2001 11.212005459756753 2002 11.953427021673896 2003 6.251322540524416 2004 7.779201553259734 2005 8.468671124045775 2006 11.565733671125786 2007 6.109676660904881 2008 5.74903896272666 2009 7.287273831645615 2010 15.084299880466123 2011 18.702461732536033 2012 9.976961174305725 2013 10.687133660928193 2014 17.36274574698345 2015 17.84155351140833 2016 13.86766096108832 2017 10.92658197954193 2018 6.311976543908167 2019 8.998479707173141 2020 11.40830594766599 2021 12.63087000450281 2022 7.8067681824695825