Year	gross (GPI)
1975	0.815789997577667
1976	0.84213000535965
1977	0.845969974994659
1978	0.847699999809265
1979	0.840210020542145
1980	0.836979985237122
1981	0.825230002403259
1982	0.819010019302368
1983	0.823369979858398
1984	0.828050017356873
1985	0.833259999752045
1986	0.847469985485077
1987	0.860979974269867
1988	0.867550015449524
1989	0.877550005912781
1990	0.883189976215363
1991	0.893339991569519
1992	0.904380023479462
1993	0.906759977340698
1994	0.922580003738403
1995	0.929740011692047
1996	0.937210023403168
1997	0.943440020084381
1998	0.950129985809326
1999	0.959249973297119
2000	0.964230000972748
2001	0.96806001663208
2002	0.969099998474121
2003	0.971310019493103
2004	0.978619992733002
2005	0.982379972934723
2006	0.987020015716553
2007	0.98879998922348
2008	0.992890000343323
2009	0.9966099858284
2010	0.993570029735565
2011	0.996550023555756
2012	0.998260021209717
2013	0.999220013618469
2014	1.00281000137329
2015	1.00207996368408
2016	1.00547003746033
2017	1.00648999214172
2018	1.00852000713348
2019	1.00861001014709
2020	1.00701999664307