Year current US$ 1960 5.080811172505139 1961 9.214753059525169 1962 6.432209910724353 1963 7.426128226643645 1964 7.7720042290971945 1965 7.966743134025414 1966 7.148523112961858 1967 4.409006328208584 1968 6.396791572702223 1969 5.218128062090685 1970 5.60154716613451 1971 8.452986437234792 1972 6.308515255180663 1973 5.710317338751428 1974 6.788983541551508 1975 15.590471483309146 1976 14.16437743230913 1977 33.267840273579964 1978 22.95841662142969 1979 28.03576319942287 1980 58.99043470206842 1981 51.66699040817666 1982 40.996269925809834 1983 20.988020967882193 1984 15.573441289411127 1985 38.76682338509793 1986 18.742185408543847 1987 18.28999988809771 1988 20.373018114879308 1989 20.669117340110347 1990 50.51073870895405 1991 61.33603942108365 1992 37.542306967969594 1993 30.224618905336378 1994 26.08700605285733 1995 18.818718533031483 1996 24.059698111172438 1997 17.2120292929568 1998 19.113894894367533 1999 24.202011393953942 2000 15.667629852785044 2001 17.07045801137535 2002 12.435748085125166 2003 19.70212383517085 2004 25.99130045860822 2005 24.074736263557828 2006 35.72565898006624 2007 39.08059771394586 2008 45.983888700584465 2009 32.92775413349869 2010 30.35589397953757 2011 43.77137021081976 2012 44.108975487705465 2013 59.42042660569679 2014 65.40850446786837 2015 43.77912279292505 2016 58.74283022533827 2017 68.33010680634561 2018 22.77613882095378 2019 20.70712762388592 2020 49.84004224205324 2021 26.059304774177846 2022 37.770333284419756