Year	gross (GPI)
1971	0.627170026302338
1972	0.655920028686523
1973	0.670469999313354
1974	0.6769899725914
1975	0.685570001602173
1976	0.696770012378693
1977	0.713779985904694
1978	0.721459984779358
1979	0.735660016536713
1980	0.745109975337982
1981	0.753769993782043
1982	0.758970022201538
1983	0.767989993095398
1984	0.774940013885498
1985	0.787000000476837
1986	0.804480016231537
1987	0.819079995155334
1988	0.827730000019073
1989	0.83652001619339
1990	0.841050028800964
1991	0.84636002779007
1992	0.856109976768494
1993	0.864090025424957
1994	0.875029981136322
1995	0.882990002632141
1996	0.892350018024445
1997	0.899209976196289
1998	0.906710028648376
1999	0.912649989128113
2000	0.916679978370667
2001	0.918299973011017
2002	0.924610018730164
2003	0.923749983310699
2004	0.925880014896393
2005	0.92509001493454
2006	0.926509976387024
2007	0.933889985084534
2008	0.936590015888214
2009	0.935899972915649
2010	0.937489986419678
2011	0.938399970531464
2012	0.9444500207901
2013	0.948409974575043
2014	0.950959980487823
2015	0.952300012111664
2016	0.949720025062561
2017	0.950929999351501
2018	0.954990029335022
2019	0.958090007305145
2020	0.969200015068054