Year	gross (GPI)
1970	0.717530012130737
1971	0.71875
1972	0.719940006732941
1973	0.721130013465881
1974	0.72869998216629
1975	0.734820008277893
1976	0.734839975833893
1977	0.738390028476715
1978	0.75135999917984
1979	0.763859987258911
1980	0.755249977111816
1981	0.745940029621124
1982	0.742529988288879
1983	0.755190014839172
1984	0.74533998966217
1985	0.737460017204285
1986	0.763029992580414
1987	0.77470999956131
1988	0.780830025672913
1989	0.789059996604919
1990	0.79271000623703
1991	0.799409985542297
1992	0.807609975337982
1993	0.813799977302551
1994	0.830299973487854
1995	0.84103000164032
1996	0.850139975547791
1997	0.861899971961975
1998	0.877420008182526
1999	0.891160011291504
2000	0.896520018577576
2001	0.899699985980988
2002	0.905969977378845
2003	0.922299981117249
2004	0.923680007457733
2005	0.932739973068237
2006	0.938350021839142
2007	0.94555002450943
2008	0.953869998455048
2009	0.965839982032776
2010	0.960309982299805
2011	0.964320003986359
2012	0.967880010604858
2013	0.98089998960495
2014	0.986010015010834
2015	0.985930025577545
2016	0.988200008869171
2017	0.98733001947403
2018	0.990419983863831
2019	0.991639971733093
2020	0.986280024051666