Year	gross (GPI)
1971	0.89138001203537
1972	0.906740009784698
1973	0.937520027160645
1974	0.924409985542297
1975	0.933019995689392
1976	0.940490007400513
1977	0.947979986667633
1978	0.954230010509491
1979	0.96340000629425
1980	0.967379987239838
1981	0.97597998380661
1982	0.99414998292923
1983	0.994849979877472
1984	0.995530009269714
1985	0.999260008335114
1986	1.00574004650116
1987	1.00935995578766
1988	1.01126003265381
1989	1.01471996307373
1990	1.00757002830505
1991	1.00601005554199
1992	1.00606000423431
1994	1.03298997879028
1995	1.03565001487732
1996	1.03456997871399
1997	1.03103005886078
1998	1.02243995666504
1999	1.01531994342804
2000	1.00786995887756
2001	1.0072900056839
2002	1.00669002532959
2003	1.00071001052856
2004	0.990279972553253
2005	0.989830017089844
2006	0.990419983863831
2007	0.994470000267029
2008	0.985790014266968
2009	0.9894899725914
2010	0.986999988555908
2011	0.98199999332428
2012	0.982550024986267
2013	1.00547003746033
2014	1.00591003894806
2015	1.00593996047974
2016	0.991609990596771
2017	1.00144994258881
2018	0.995500028133392
2019	0.996649980545044
2020	0.994910001754761