Year	gross (GPI)
1971	0.776579976081848
1976	0.84486997127533
1977	0.8646399974823
1978	0.880819976329803
1979	0.89138001203537
1980	0.895619988441467
1981	0.899290025234222
1982	0.905610024929047
1983	0.907769978046417
1984	0.908879995346069
1985	0.913770020008087
1986	0.92451000213623
1987	0.936179995536804
1988	0.942659974098206
1989	0.949400007724762
1990	0.956309974193573
1991	0.960860013961792
1992	0.952400028705597
1999	0.956330001354218
2000	0.93997997045517
2001	0.963789999485016
2002	0.976870000362396
2003	0.980130016803741
2004	0.997940003871918
2005	1.00641000270844
2006	1.02309000492096
2007	1.00548994541168
2008	1.0050300359726
2009	1.00713002681732
2010	1.01434004306793
2011	1.02654004096985
2012	1.02889001369476
2013	1.03242003917694
2014	1.03743004798889
2015	1.02611005306244
2016	1.01540005207062
2017	1.01505994796753
2018	1.01159000396729
2019	1.00995004177094
2021	1.02298998832703