Year current US$ 1960 4.9910980109975736 1961 6.663598848065805 1962 7.9077215596749175 1963 7.465164153953867 1964 5.294513753928623 1965 6.037061509439025 1966 6.308748254796811 1967 5.987012114443255 1968 5.153748623293184 1969 4.9579529830082905 1970 4.946401410083344 1971 5.599291449599101 1972 6.252279651421109 1973 2.180484999854984 1974 1.2914457509583304 1975 1.474280539736051 1976 3.111775218256899 1977 2.2473970724598518 1978 4.152301741137646 1979 13.509008558642233 1980 21.613747223280697 1981 16.164287132480887 1982 14.091406459687882 1983 7.5672344931932 1984 4.998881149593413 1985 3.6623800980520587 1986 6.768890766914547 1987 7.392563345318235 1988 5.390247756265786 1989 2.7184948416530546 1990 24.001299009673083 1991 29.103324660165914 1992 6.32783479954148 1993 7.814331689326908 1994 3.4016321849362146 1995 5.287200182623801 1996 4.081349309049111 1997 0.11031795344800939 1998 0.45130150199353325 1999 0.19703851595438454 2000 5.1248140634649175 2001 2.0478847683321577 2002 4.143742121906698 2003 2.507053996485429 2004 4.26170517452128 2005 5.8122646542128305 2006 8.178866484721278 2007 11.42476550719244 2008 15.810463833824729 2009 18.836548124963095 2010 14.350001549316092 2011 44.30219949945118 2012 41.39854586335312 2013 37.398935623922156 2014 44.65775957906457 2015 27.375372637527636 2016 45.52450639296996 2017 39.33724190534453 2018 14.690715255506625 2019 8.480318924334785 2020 6.503592599899274 2021 12.591489119861194 2022 9.417166848961706