Year	gross (GPI)
1971	1.0847100019455
1972	1.07801997661591
1973	1.06844997406006
1974	1.00657999515533
1975	1.07249999046326
1977	1.08452999591827
1978	1.09437000751495
1979	1.09829998016357
1980	1.10590994358063
1981	1.1952999830246
1982	1.10910999774933
1983	1.10528004169464
1985	1.08605003356934
1986	1.08176004886627
1987	1.07492005825043
1988	1.07041001319885
1989	1.06836998462677
1990	1.06582999229431
1991	1.05263996124268
1992	1.04648995399475
1993	1.03759002685547
1994	0.992669999599457
1995	0.985979974269867
1996	0.988380014896393
1997	0.989260017871857
1998	0.991609990596771
1999	0.999790012836456
2000	0.999549984931946
2001	1.00157999992371
2002	1.00369000434875
2003	1.00878000259399
2004	1.00541996955872
2005	1.00385999679565
2006	0.999970018863678
2007	1.00177001953125
2008	1.00341999530792
2009	1.00396001338959
2010	1.00995004177094
2011	1.00878000259399
2012	1.0056300163269
2013	1.01165997982025
2014	1.01516997814178
2015	1.01034998893738
2016	1.00823998451233
2017	1.00760996341705
2018	1.00562000274658
2019	1.00145995616913
2020	1.00024998188019