Year	gross (GPI)
1971	0.781740009784698
1972	0.861169993877411
1973	0.841830015182495
1974	0.831489980220795
1975	0.823849976062775
1976	0.839890003204346
1977	0.852069973945618
1978	0.855610013008118
1979	0.891420006752014
1980	0.936320006847382
1981	0.963249981403351
1982	0.996680021286011
1983	0.999880015850067
1984	0.974810004234314
1985	0.935649991035461
1986	0.909219980239868
1987	0.906780004501343
1988	0.92918998003006
1989	0.952920019626617
1990	0.972060024738312
1991	0.947080016136169
1992	1.00100994110107
1993	1.02517998218536
1994	1.01090002059937
1995	1.01175999641418
1996	0.909860014915466
1997	0.885590016841888
1998	0.897880017757416
1999	0.94199001789093
2000	1.02240002155304
2001	1.09063994884491
2002	1.1108900308609
2003	1.12786996364594
2004	1.09379005432129
2005	1.03770005702972
2006	0.997579991817474
2007	0.974979996681213
2008	0.971780002117157
2009	0.973950028419495
2010	0.980260014533997
2011	0.997619986534119
2012	1.01135003566742
2013	1.02244997024536
2014	1.02143001556396
2015	1.03220999240875
2016	1.03975999355316
2017	1.03327000141144
2018	1.10301995277405
2019	1.15234994888306
2020	1.12817001342773
2021	1.15374994277954