Year	current US$
1970	2.849849660485069
1971	3.177182377870155
1972	3.7732389374239745
1973	4.283144771412324
1974	6.539768865295804
1975	9.38980097513248
1976	8.233372554803694
1977	10.02818718263152
1978	12.773734988637623
1979	17.17487986272726
1980	20.216016442514576
1981	19.122545830020492
1982	19.68712921330017
1983	18.612568095932797
1984	17.63358448427984
1985	20.374965176689233
1986	22.785512727525855
1987	26.57618716684904
1988	29.10242507538167
1989	28.052248335346967
1990	33.82070265021183
1991	32.003764896435236
1992	34.9006424279602
1993	30.660933316070295
1994	29.93545359490243
1995	30.55722970073137
1996	22.642703908538024
1997	21.561949517633362
1998	20.118040578554663
1999	19.110250711254427
2000	19.908113285840173
2001	20.655488132433756
2002	26.98389077295962
2003	38.086110758784415
2004	36.49259622029299
2005	35.89914089274043
2006	39.30243928858636
2007	42.46632932139787
2008	47.76607640968566
2009	49.357308364220074
2010	47.71609327222228
2011	53.05720339090284
2012	47.46683225899069
2013	51.43154407854815
2014	44.37627210233054
2015	42.494586655517686
2016	40.671740639251354
2017	44.06441868538134
2018	42.36273490129212
2019	45.26523432692683