Year	constant 2010 US$
1968	14252.6202890417
1969	14540.8206997835
1970	22133.9049242035
1971	25518.723374727
1972	29935.7968226558
1973	35405.0370442769
1974	39152.0782044791
1975	33902.4233273083
1976	37981.3234026997
1977	38669.5225583174
1978	34789.6781434925
1979	36843.9255745131
1980	36703.1433368183
1981	35165.5314356646
1982	26158.1917870167
1983	20622.7170144053
1984	18525.1325591437
1985	15818.8407194567
1986	17604.0628019166
1987	15695.1819600488
1988	17017.1498628873
1989	16287.1839082331
1990	18105.9059666821
1991	20154.1657299259
1992	20339.374326988
1993	19519.1968143153
1994	19142.0630974531
1995	18745.963301868
1996	18841.0292563939
1997	18682.5851596284
1998	18857.6290970743
1999	17778.41410464
2000	18352.0271397081
2001	17669.1180001687
2002	16696.4103852427
2003	18034.7245219
2004	18901.0131046053
2005	19381.8519639916
2006	19367.5827543478
2007	19187.8067947643
2008	19832.6513319799
2009	18883.199839421
2010	19262.5476811757
2011	20553.9053742816
2012	21006.6370090509
2013	20929.4968690033
2014	21087.3544122692
2015	21399.1040059788
2016	21270.4714040551
2017	20693.9391318252
2018	20775.2018126319