Year	gross (GPI)
1970	0.581910014152527
1971	0.615459978580475
1972	0.633099973201752
1973	0.659990012645721
1977	0.722029983997345
1978	0.753329992294312
1979	0.745639979839325
1980	0.743489980697632
1981	0.751739978790283
1982	0.747340023517609
1983	0.701300024986267
1984	0.676490008831024
1986	0.797990024089813
1987	0.812940001487732
1989	0.832419991493225
1990	0.782169997692108
1999	0.823350012302399
2000	0.815140008926392
2001	0.827269971370697
2002	0.81156998872757
2004	0.82804000377655
2005	0.839640021324158
2006	0.849070012569427
2007	0.855579972267151
2008	0.873030006885529
2009	0.887960016727448
2010	0.897220015525818
2011	0.908169984817505
2012	0.95440000295639
2013	0.952579975128174
2014	0.956820011138916
2016	0.930320024490356
2018	0.969380021095276