Year	gross (GPI)
1971	0.66074001789093
1972	0.654749989509583
1973	0.655489981174469
1974	0.649680018424988
1975	0.653190016746521
1976	0.664979994297028
1977	0.668420016765594
1978	0.681729972362518
1979	0.701619982719421
1980	0.712350010871887
1981	0.735360026359558
1982	0.761600017547607
1983	0.781759977340698
1984	0.805769979953766
1985	0.820060014724731
1986	0.835470020771027
1987	0.839420020580292
1988	0.845000028610229
1989	0.858560025691986
1990	0.870360016822815
1991	0.882470011711121
1992	0.893540024757385
1993	0.906669974327087
1994	0.916750013828278
1995	0.927190005779266
1996	0.938040018081665
1997	0.946850001811981
1998	0.951030015945435
1999	0.957180023193359
2000	0.963069975376129
2001	0.973169982433319
2002	0.977850019931793
2003	0.982389986515045
2004	0.984730005264282
2005	0.985859990119934
2006	0.98565000295639
2007	0.985230028629303
2008	0.988030016422272
2009	0.994870007038116
2010	0.996079981327057
2011	0.998369991779327
2012	1.00481998920441
2013	0.99848997592926
2014	1.00071001052856
2015	1.00042998790741
2016	1.00265002250671
2017	0.99575001001358
2018	0.991370022296906
2020	0.984579980373383
2021	0.982280015945435