Year	gross (GPI)
1970	0.759819984436035
1971	0.759549975395203
1972	0.760240018367767
1973	0.759370028972626
1974	0.757589995861053
1975	0.793200016021729
1976	0.813390016555786
1977	0.819410026073456
1978	0.818880021572113
1979	0.819760024547577
1980	0.822560012340546
1981	0.824129998683929
1982	0.822880029678345
1983	0.820760011672974
1984	0.8262699842453
1985	0.832249999046326
1986	0.847490012645721
1987	0.854420006275177
1988	0.858529984951019
1989	0.861000001430511
1990	0.86668998003006
1991	0.876489996910095
1992	0.88358998298645
1993	0.890079975128174
1994	0.894460022449493
1995	0.897170007228851
1996	0.89995002746582
1997	0.905390024185181
1998	0.907620012760162
1999	0.912590026855469
2000	0.915139973163605
2001	0.920069992542267
2002	0.922070026397705
2003	0.945119976997375
2004	0.946739971637726
2005	0.94980001449585
2006	0.953740000724792
2007	0.956789970397949
2008	0.964349985122681
2009	0.969470024108887
2010	0.972150027751923
2011	0.974200010299683
2012	0.978900015354156
2013	0.997659981250763
2014	0.99753999710083
2015	0.999119997024536
2016	1.00822997093201
2017	1.0058399438858
2018	0.980239987373352
2019	0.981289982795715
2020	0.980539977550507