Year	gross (GPI)
1971	0.790610015392303
1972	0.793799996376038
1973	0.869620025157928
1974	0.880190014839172
1975	0.94937002658844
1976	0.963429987430573
1977	0.981620013713837
1978	0.991859972476959
1979	0.95455002784729
1980	1.03736996650696
1981	1.04206001758575
1982	1.00417995452881
1983	1.07165002822876
1984	1.04639005661011
1985	1.0487699508667
1986	1.07936000823975
1987	1.082239985466
1988	1.07719004154205
1989	1.0727299451828
1990	1.05991005897522
1991	1.06719994544983
1992	1.08000004291534
1993	1.08521997928619
1994	1.08625996112823
1995	1.08535003662109
1996	1.10759997367859
1997	1.06201994419098
1998	1.07260000705719
1999	1.07090997695923
2000	1.06745004653931
2001	1.06340003013611
2002	1.07070004940033
2003	1.06169998645782
2004	1.067999958992
2005	1.06554996967316
2006	1.06374001502991
2007	1.0670200586319
2008	1.06245005130768
2009	1.04980003833771
2010	1.0267299413681
2011	1.01406002044678
2012	1.0079300403595
2013	1.00271999835968
2014	1.00092995166779
2015	0.993809998035431
2016	1.00346994400024
2017	1.01362001895905
2018	1.01873004436493
2019	1.02888000011444
2020	1.02936005592346