Year	gross (GPI)
1971	0.973010003566742
1972	0.997229993343353
1973	1.01160001754761
1974	0.842729985713959
1975	0.921689987182617
1976	0.998449981212616
1977	0.97759997844696
1978	0.971809983253479
1979	0.974009990692139
1980	0.987119972705841
1981	0.99779999256134
1982	0.968810021877289
1983	0.941789984703064
1984	0.997959971427917
1985	0.959519982337952
1989	1.00812995433807
1990	0.992579996585846
1992	1.00150001049042
1999	0.983439981937408
2000	0.981130003929138
2001	0.988259971141815
2002	0.990760028362274
2003	0.979680001735687
2004	0.980279982089996
2005	0.996190011501312
2006	0.980289995670319
2007	1.00662994384766
2008	1.00134003162384
2009	1.00673997402191
2010	1.01582002639771
2011	1.00073003768921
2014	1.00442004203796
2015	0.993019998073578
2016	0.997709989547729
2017	0.965030014514923
2018	0.963280022144318
2019	0.958050012588501
2020	0.969879984855652
2021	0.971660017967224