Year	gross (GPI)
1971	1.05054998397827
1972	0.994220018386841
1973	0.997030019760132
1974	0.999629974365234
1975	1.00809001922607
1976	1.00224995613098
1977	1.00383996963501
1978	1.01279997825623
1979	1.01876997947693
1980	1.01855003833771
1981	1.02609002590179
1982	1.03224003314972
1983	1.02374005317688
1984	1.03453004360199
1985	1.03105998039246
1986	1.02851998806
1987	1.02951002120972
1988	1.02693998813629
1989	1.02925002574921
1990	1.02295005321503
1991	1.01735997200012
1992	1.0079699754715
1993	0.988240003585815
1994	0.98539000749588
1995	0.972350001335144
1996	0.972379982471466
1997	0.98089998960495
1998	1.00295996665955
1999	1.01014995574951
2000	1.01294994354248
2001	1.01139998435974
2002	1.0110399723053
2003	1.00978994369507
2004	1.01470994949341
2005	1.00622999668121
2006	1.00147998332977
2007	0.994400024414063
2008	0.990409970283508
2009	0.989839971065521
2010	0.9930499792099
2011	0.994620025157928
2012	0.994369983673096
2013	0.983449995517731
2014	0.982230007648468
2015	0.985490024089813
2016	0.985369980335236
2017	0.977559983730316
2018	0.977540016174316
2019	0.975560009479523
2020	0.977140009403229