Year	gross (GPI)
1971	1.00021004676819
1972	0.993950009346008
1973	1.0062700510025
1974	1.0075900554657
1975	1.0066499710083
1976	1.04375004768372
1977	1.03767001628876
1978	1.04089999198914
1979	1.03541994094849
1980	1.04905998706818
1981	1.05208003520966
1982	1.06254994869232
1983	1.06164002418518
1984	1.06119000911713
1985	1.06610000133514
1987	1.01816999912262
1988	1.01219999790192
1989	1.01955997943878
1990	1.02301001548767
1991	1.02400994300842
1992	1.02302002906799
1993	1.08131003379822
1994	1.07839000225067
1995	1.08776998519897
1996	1.09906995296478
1997	1.1088399887085
1998	1.15064001083374
1999	1.15224003791809
2000	1.15218997001648
2001	1.14743995666504
2002	1.12451994419098
2003	1.10784995555878
2004	1.0135999917984
2005	0.996159970760345
2006	0.996320009231567
2007	0.994740009307861
2008	0.994090020656586
2009	0.993409991264343
2010	0.991919994354248
2011	0.992640018463135
2012	0.99234002828598
2013	1.09826004505157
2014	1.09630000591278
2015	1.09107995033264
2016	1.07133996486664
2017	1.03990995883942
2018	1.04197001457214
2019	1.05411005020142
2020	1.06958997249603