Year	gross (GPI)
1973	0.771030008792877
1974	0.766439974308014
1975	0.841470003128052
1976	0.88059002161026
1977	0.886179983615875
1978	0.879480004310608
1979	0.870299994945526
1980	0.87033998966217
1981	0.865320026874542
1982	0.857819974422455
1983	0.859109997749329
1984	0.863940000534058
1985	0.867240011692047
1986	0.889129996299744
1987	0.898580014705658
1988	0.906109988689423
1989	0.915120005607605
1990	0.921739995479584
1991	0.93383002281189
1992	0.942969977855682
1993	0.943650007247925
1994	0.950529992580414
1995	0.954620003700256
1996	0.96017998456955
1997	0.967249989509583
1998	0.968779981136322
1999	0.974629998207092
2000	0.979269981384277
2001	0.984660029411316
2002	0.985580027103424
2003	0.987500011920929
2004	0.990840017795563
2005	0.987399995326996
2006	0.98539000749588
2007	0.982479989528656
2008	0.98404997587204
2009	0.982940018177032
2010	0.991789996623993
2011	0.993960022926331
2012	0.991199970245361
2013	0.994239985942841
2014	0.994329988956451
2015	0.992500007152557
2016	0.995289981365204
2017	0.996730029582977
2018	0.997810006141663
2019	0.99795001745224
2020	0.99686998128891