Year	gross (GPI)
1971	1.03421998023987
1972	1.03428995609283
1973	1.07291996479034
1974	1.00152003765106
1975	1.03438997268677
1977	1.03666996955872
1978	1.0443400144577
1979	1.04165995121002
1980	1.04770994186401
1981	1.09122002124786
1982	1.04730999469757
1983	1.04832994937897
1985	1.03999996185303
1986	1.03586995601654
1987	1.03451001644135
1988	1.03297996520996
1989	1.03167998790741
1990	1.02837002277374
1991	1.02306997776031
1992	1.01954996585846
1993	1.0150500535965
1994	0.987689971923828
1995	0.984420001506805
1996	0.98675000667572
1997	0.98921000957489
1998	0.990629971027374
1999	0.995480000972748
2000	0.996110022068024
2001	0.997730016708374
2002	0.999239981174469
2003	1.00241994857788
2004	1.0014899969101
2005	0.998440027236938
2006	0.995469987392426
2007	0.997829973697662
2008	0.997569978237152
2009	0.998329997062683
2010	1.00078999996185
2011	1.00325000286102
2012	1.00304996967316
2013	1.00567996501923
2014	1.00685000419617
2015	1.00341999530792
2016	1.00250005722046
2017	1.00194001197815
2018	1.00080001354218
2019	0.998740017414093
2020	0.997049987316132