Year	U.S. dollars (Billions)
1980	-0.139
1981	-0.746
1982	0.991
1983	-1.177
1984	-1.159
1985	-0.491
1986	-0.210
1987	-0.200
1988	-0.709
1989	-0.603
1990	-1.098
1991	-2.524
1992	-2.765
1993	-0.460
1994	-0.562
1995	-1.071
1996	-1.317
1997	-5.036
1998	-5.104
1999	-3.328
2000	-2.996
2001	-3.418
2002	-3.179
2003	-3.626
2004	-3.807
2005	-2.424
2006	-1.943
2007	-2.403
2008	-5.023
2009	-7.947
2010	-7.955
2011	-6.551
2012	-11.407
2013	-13.121
2014	-13.883
2015	-9.918
2016	-12.042
2017	-14.030
2018	-15.850
2019	-14.375
2020	-3.944
2021	-3.576
2022	-7.859