Year	gross (GPI)
1970	0.97639000415802
1971	0.976989984512329
1972	0.97545999288559
1973	0.981500029563904
1974	0.979820013046265
1975	0.978670001029968
1976	0.982330024242401
1977	0.983609974384308
1978	0.98429000377655
1979	0.988359987735748
1980	0.991659998893738
1981	0.991029977798462
1982	0.98878002166748
1983	0.982699990272522
1984	0.984860002994537
1985	0.989530026912689
1986	0.989780008792877
1987	0.986720025539398
1988	0.985960006713867
1989	0.986500024795532
1990	0.991770029067993
1991	0.985080003738403
1992	0.986440002918243
1993	0.984790027141571
1994	0.985310018062592
1995	0.98513001203537
1996	0.984730005264282
1997	0.988460004329681
1998	0.992479979991913
1999	0.994870007038116
2000	0.985210001468658
2001	0.989130020141602
2002	0.992250025272369
2003	0.990949988365173
2004	0.989269971847534
2005	0.986940026283264
2006	0.992290019989014
2007	0.992659986019135
2008	0.992089986801147
2009	0.994120001792908
2010	0.99397999048233
2011	0.993619978427887
2012	0.993650019168854
2013	0.994740009307861
2014	0.996280014514923
2015	0.997569978237152
2016	0.998090028762817
2017	0.995609998703003
2018	0.997200012207031
2019	1.00034999847412
2020	0.997340023517609