Year	current US$
1967	460
1968	510
1969	550
1970	560
1971	530
1972	560
1973	640
1974	850
1975	1110
1976	1310
1977	1410
1978	1520
1979	1820
1980	1860
1981	1870
1982	1570
1983	1400
1984	1310
1985	1310
1986	1440
1987	1740
1988	1850
1989	1910
1990	2290
1991	2570
1992	2920
1993	3120
1994	2650
1995	2810
1996	2880
1997	3140
1998	3390
1999	3540
2000	4260
2001	3530
2002	3540
2003	3900
2004	5210
2005	6750
2006	7790
2007	8880
2008	9770
2009	9550
2010	10380
2011	11190
2012	11880
2013	12570
2014	12630
2015	12080
2016	11340
2017	11090
2018	10650
2019	9800
2020	9160
2021	10010
2022	10640
2023	11650