Year	gross (GPI)
1971	0.985260009765625
1972	0.987030029296875
1973	0.989430010318756
1974	0.989989995956421
1975	0.991119980812073
1976	0.992999970912933
1977	0.992519974708557
1978	0.992470026016235
1979	0.991159975528717
1980	0.993929982185364
1981	0.995959997177124
1982	0.997879981994629
1983	0.996339976787567
1984	0.997300028800964
1985	0.996930003166199
1986	0.996079981327057
1987	0.991879999637604
1988	0.99575001001358
1989	0.995809972286224
1990	1.00104999542236
1991	0.998049974441528
1992	0.998749971389771
1993	1.02799999713898
1994	1.03956997394562
1995	0.985599994659424
1996	0.989340007305145
1997	0.996070027351379
1998	0.988420009613037
1999	0.993019998073578
2000	0.998009979724884
2001	0.991280019283295
2002	0.977970004081726
2003	0.988730013370514
2004	0.991050004959106
2005	0.986469984054565
2006	0.98580002784729
2007	0.987450003623962
2008	0.988099992275238
2009	0.988569974899292
2010	0.990469992160797
2011	0.988560020923615
2012	0.992150008678436
2013	0.995169997215271
2014	0.99506002664566
2015	0.995710015296936
2016	1.00004005432129
2017	0.969990015029907
2018	0.96739000082016
2019	0.981119990348816
2020	0.999210000038147