Year	gross (GPI)
1970	0.834850013256073
1971	0.834119975566864
1972	0.835210025310516
1973	0.860790014266968
1974	0.882589995861053
1975	0.912559986114502
1976	0.938109993934631
1977	0.964540004730225
1978	0.992479979991913
1979	0.996519982814789
1980	1.00513994693756
1981	1.0153900384903
1982	1.01050996780396
1983	1.0130900144577
1984	1.01099002361298
1985	1.00958001613617
1986	1.01379001140594
1987	1.01522994041443
1988	1.01147997379303
1989	1.00765001773834
1990	1.005499958992
1991	1.00973999500275
1992	1.0095100402832
1993	1.00554001331329
1994	1.00013995170593
1995	1.00766003131866
1996	1.00654995441437
1997	1.00952994823456
1998	1.01514995098114
1999	1.01387000083923
2000	1.00908005237579
2001	1.0072900056839
2002	1.00297999382019
2003	1.0066499710083
2004	1.01040995121002
2005	1.00854003429413
2006	1.00049996376038
2007	0.999400019645691
2008	0.999109983444214
2009	0.999580025672913
2010	0.997189998626709
2011	0.994949996471405
2012	0.995090007781982
2013	0.999629974365234
2014	1.00198996067047
2015	1.00063002109528
2016	0.99397999048233
2017	0.99261999130249
2018	0.99533998966217
2019	0.991680026054382
2020	0.993889987468719