Year	gross (GPI)
1971	0.60096001625061
1972	0.599470019340515
1973	0.655350029468536
1974	0.716319978237152
1975	0.782149970531464
1976	0.853269994258881
1977	0.933539986610413
1978	1.02250003814697
1979	1.03103005886078
1980	1.04111003875732
1981	1.05120003223419
1982	1.04657995700836
1983	1.04053997993469
1984	1.03210997581482
1985	1.02256000041962
1986	1.02945005893707
1987	1.02497005462646
1988	1.01669001579285
1989	1.01025998592377
1990	1.00197005271912
1991	1.01592004299164
1992	1.0059700012207
1993	0.997860014438629
1994	0.992799997329712
1995	1.01310002803802
1996	1.0003399848938
1997	1.01572000980377
1998	1.03286004066467
1999	1.02908003330231
2000	1.01610994338989
2001	1.00520002841949
2002	0.993499994277954
2003	1.00527000427246
2004	1.01707994937897
2005	1.0145800113678
2006	0.994040012359619
2007	0.994859993457794
2008	0.995689988136292
2009	1.01180994510651
2010	1.00915002822876
2011	1.00652003288269
2012	1.00479996204376
2013	1.00243997573853
2014	1.01122999191284
2015	1.01020002365112
2016	0.995999991893768
2017	0.996519982814789
2018	0.992389976978302
2019	0.985350012779236
2020	0.981869995594025