Year	gross (GPI)
1971	1.0077600479126
1972	1.00794994831085
1973	1.01125001907349
1974	1.00976002216339
1975	1.0100200176239
1976	1.01136004924774
1977	1.01287996768951
1978	1.01417994499207
1979	1.0168000459671
1980	1.01861000061035
1981	1.0207200050354
1982	1.02098000049591
1983	1.02192997932434
1984	1.02447998523712
1985	1.0254100561142
1986	1.02002000808716
1987	1.02249002456665
1988	1.02585995197296
1989	1.02746999263763
1990	1.03126001358032
1991	1.0311199426651
1992	1.02108001708984
1993	1.03076994419098
1994	0.982100009918213
1995	0.982699990272522
1996	0.980970025062561
1997	0.980750024318695
1998	0.980870008468628
1999	0.977909982204437
2000	0.978760004043579
2001	0.979319989681244
2002	0.978829979896545
2003	0.976480007171631
2004	0.974720001220703
2005	0.977219998836517
2006	0.979059994220734
2007	0.982479989528656
2008	0.985270023345947
2009	0.989939987659454
2010	0.996559977531433
2011	0.999239981174469
2012	0.999819993972778
2015	0.999580025672913
2016	1.00006997585297
2017	0.999859988689423
2018	0.99905002117157
2019	1.00007998943329
2020	0.998040020465851