Year	gross (GPI)
1970	0.593580007553101
1971	0.605040013790131
1972	0.619459986686707
1973	0.637279987335205
1974	0.646260023117065
1975	0.652629971504211
1976	0.657989978790283
1977	0.672060012817383
1978	0.711049973964691
1979	0.723290026187897
1980	0.728879988193512
1981	0.73827999830246
1982	0.740190029144287
1983	0.714370012283325
1984	0.70345002412796
1985	0.731100022792816
1986	0.757409989833832
1987	0.760129988193512
1988	0.745589971542358
1989	0.765900015830994
1990	0.750379979610443
1991	0.760230004787445
1992	0.768050014972687
1993	0.771070003509521
1994	0.77877002954483
1995	0.786779999732971
1996	0.798590004444122
1997	0.803510010242462
1998	0.803600013256073
1999	0.805760025978088
2000	0.810270011425018
2001	0.817569971084595
2002	0.808459997177124
2003	0.830229997634888
2004	0.830969989299774
2005	0.845830023288727
2006	0.85631000995636
2007	0.865440011024475
2008	0.875270009040833
2009	0.888220012187958
2010	0.88944000005722
2011	0.89411997795105
2012	0.913789987564087
2013	0.913619995117188
2014	0.916899979114532
2015	0.915780007839203
2016	0.907649993896484
2017	0.91746997833252
2018	0.924539983272552
2019	0.930109977722168
2020	0.926079988479614