Year	gross (GPI)
1970	0.75220000743866
1971	0.75204998254776
1972	0.752399981021881
1973	0.752059996128082
1974	0.753059983253479
1975	0.782429993152618
1976	0.797150015830994
1977	0.80103999376297
1978	0.803690016269684
1979	0.808019995689392
1980	0.806729972362518
1981	0.804000020027161
1982	0.800270020961761
1983	0.802569985389709
1984	0.802470028400421
1985	0.804769992828369
1986	0.8230100274086
1987	0.830810010433197
1988	0.836600005626678
1989	0.841300010681152
1990	0.846419990062714
1991	0.855109989643097
1992	0.862810015678406
1993	0.869340002536774
1994	0.879149973392487
1995	0.885640025138855
1996	0.891420006752014
1997	0.899930000305176
1998	0.907920002937317
1999	0.91550999879837
2000	0.919040024280548
2001	0.923529982566834
2002	0.927479982376099
2003	0.949509978294373
2004	0.952019989490509
2005	0.956229984760284
2006	0.960929989814758
2007	0.966499984264374
2008	0.97503000497818
2009	0.983229994773865
2010	0.981700003147125
2011	0.984430015087128
2012	0.988600015640259
2013	1.00685000419617
2014	1.00953996181488
2015	1.00934994220734
2016	1.01663994789124
2017	1.01482999324799
2018	1.0001300573349
2019	1.00152003765106
2020	0.998199999332428