Year	gross (GPI)
1971	0.728129982948303
1972	0.749939978122711
1973	0.77021998167038
1974	0.787349998950958
1975	0.802820026874542
1976	0.811649978160858
1977	0.818849980831146
1978	0.827149987220764
1979	0.830479979515076
1981	0.837249994277954
1982	0.857299983501434
1984	0.881429970264435
1985	0.895730018615723
1986	0.903949975967407
1987	0.903949975967407
1988	0.907079994678497
1989	0.906759977340698
1990	0.908320009708405
1991	0.908290028572083
1992	0.909529983997345
1993	0.91347998380661
1994	0.922129988670349
1995	0.923629999160767
1997	0.916000008583069
1999	0.910109996795654
2000	0.910889983177185
2001	0.920939981937408
2002	0.929390013217926
2003	0.935090005397797
2004	0.944769978523254
2005	0.950139999389648
2006	0.95958000421524
2007	0.967989981174469
2008	0.973450005054474
2009	0.981299996376038
2010	0.986129999160767
2011	0.990540027618408
2012	0.98566997051239
2013	0.993340015411377
2014	0.995429992675781
2015	0.993149995803833
2016	0.993809998035431
2017	0.989870011806488
2018	0.988709986209869
2019	0.98786997795105
2020	0.985870003700256