Year	gross (GPI)
1970	1.03677999973297
1971	1.00599002838135
1972	1.00030994415283
1973	1.01001000404358
1974	0.994279980659485
1975	1.00260996818542
1976	1.00595998764038
1977	1.01864004135132
1978	1.01406002044678
1979	1.00424003601074
1980	1.00162994861603
1981	0.992829978466034
1982	1.00473999977112
1983	0.995429992675781
1984	0.999300003051758
1986	1.00231003761292
1987	1.00815999507904
1988	1.0202100276947
1991	1.08191001415253
1999	1.01268994808197
2000	1.01135003566742
2001	0.996280014514923
2002	0.993160009384155
2003	0.997709989547729
2004	0.998170018196106
2005	1.0014899969101
2006	1.00525999069214
2007	0.999800026416779
2008	1.0100599527359
2010	1.01039004325867
2011	1.02051997184753
2012	1.00278997421265
2013	1.00555002689362
2014	1.00258004665375
2015	0.998950004577637
2016	0.996919989585876
2017	0.994459986686707
2018	0.975750029087067
2019	0.987349987030029
2020	0.986010015010834