Year	gross (GPI)
1970	0.453610002994537
1971	0.451270014047623
1972	0.452490001916885
1973	0.454739987850189
1974	0.459839999675751
1975	0.460130006074905
1976	0.465999990701675
1977	0.439579993486404
1978	0.434179991483688
1979	0.433730006217957
1980	0.456939995288849
1981	0.446599990129471
1982	0.475930005311966
1983	0.498199999332428
1984	0.524240016937256
1985	0.523779988288879
1986	0.550279974937439
1987	0.553120017051697
1988	0.566600024700165
1989	0.579739987850189
1990	0.58244001865387
1991	0.600300014019012
1992	0.619599997997284
1993	0.634299993515015
1994	0.644450008869171
1995	0.686160027980804
1996	0.70661997795105
1997	0.72776997089386
1998	0.750169992446899
1999	0.767690002918243
2000	0.787329971790314
2001	0.792739987373352
2002	0.804459989070892
2003	0.803870022296906
2004	0.774049997329712
2005	0.792270004749298
2006	0.791390001773834
2007	0.798829972743988
2008	0.817449986934662
2009	0.818880021572113
2010	0.843829989433289
2011	0.86379998922348
2012	0.872330009937286
2013	0.875400006771088
2014	0.884450018405914
2015	0.902599990367889
2016	0.904749989509583
2017	0.922569990158081
2018	0.925639986991882
2019	0.925050020217896
2020	0.932940006256104