Year	gross (GPI)
1970	0.534569978713989
1971	0.536729991436005
1972	0.543110013008118
1973	0.550970017910004
1974	0.556169986724854
1975	0.558539986610413
1976	0.561680018901825
1977	0.55019998550415
1978	0.550750017166138
1979	0.555819988250732
1980	0.561680018901825
1981	0.560459971427917
1982	0.577669978141785
1983	0.564629971981049
1984	0.563669979572296
1985	0.593100011348724
1986	0.638310015201569
1987	0.648239970207214
1988	0.654330015182495
1989	0.658900022506714
1990	0.662060022354126
1991	0.675390005111694
1992	0.685720026493073
1993	0.696919977664948
1994	0.705299973487854
1995	0.731509983539581
1996	0.747470021247864
1997	0.76503998041153
1998	0.780749976634979
1999	0.797309994697571
2000	0.805109977722168
2001	0.810130000114441
2002	0.810069978237152
2003	0.822309970855713
2004	0.805909991264343
2005	0.823379993438721
2006	0.822679996490479
2007	0.819689989089966
2008	0.838769972324371
2009	0.848049998283386
2010	0.860019981861115
2011	0.86651998758316
2012	0.875999987125397
2013	0.876950025558472
2014	0.887170016765594
2015	0.900520026683807
2016	0.903519988059998
2017	0.917410016059875
2018	0.927389979362488
2019	0.929289996623993
2020	0.934970021247864