Year	gross (GPI)
1975	0.714540004730225
1976	0.71425998210907
1977	0.735719978809357
1978	0.767870008945465
1979	0.763310015201569
1980	0.748149991035461
1981	0.719659984111786
1982	0.712149977684021
1983	0.725709974765778
1984	0.732879996299744
1985	0.746630012989044
1986	0.745400011539459
1987	0.77156001329422
1988	0.777419984340668
1989	0.788699984550476
1990	0.790180027484894
1991	0.797999978065491
1992	0.816309988498688
1993	0.824869990348816
1994	0.860930025577545
1995	0.877579987049103
1996	0.892000019550323
1997	0.898940026760101
1998	0.91719001531601
1999	0.934509992599487
2000	0.94252997636795
2001	0.947019994258881
2002	0.951470017433167
2003	0.956290006637573
2004	0.969510018825531
2005	0.982020020484924
2006	0.993499994277954
2007	0.99975997209549
2008	1.00618004798889
2009	1.01511001586914
2010	0.997229993343353
2011	1.0011500120163
2012	1.00841999053955
2013	1.00671005249023
2014	1.01449000835419
2015	1.01515996456146
2016	1.01972997188568
2017	1.02002000808716
2018	1.02274000644684
2019	1.0223400592804
2020	1.01958000659943