Year	gross (GPI)
1970	0.64411997795105
1971	0.641430020332336
1972	0.651269972324371
1973	0.656520009040833
1974	0.664740025997162
1975	0.668690025806427
1976	0.671259999275208
1977	0.682889997959137
1978	0.692489981651306
1979	0.694289982318878
1980	0.703670024871826
1981	0.711849987506866
1982	0.740209996700287
1983	0.741379976272583
1984	0.747650027275085
1985	0.736869990825653
1986	0.743260025978088
1987	0.762099981307983
1988	0.748549997806549
1989	0.753949999809265
1990	0.755490005016327
1991	0.765640020370483
1992	0.765470027923584
1993	0.768180012702942
1994	0.769779980182648
1995	0.753440022468567
1996	0.745540022850037
1997	0.75297999382019
1998	0.755219995975494
1999	0.77863997220993
2000	0.790260016918182
2001	0.797399997711182
2002	0.802450001239777
2003	0.813510000705719
2004	0.810779988765717
2005	0.842480003833771
2006	0.858919978141785
2007	0.864149987697601
2008	0.876950025558472
2009	0.88933002948761
2010	0.896480023860931
2011	0.900150001049042
2012	0.905979990959167
2013	0.910019993782043
2014	0.912800014019012
2015	0.921909987926483
2016	0.9237300157547
2017	0.922850012779236
2018	0.919250011444092
2019	0.922730028629303
2020	0.926339983940125