Year	gross (GPI)
1970	0.617680013179779
1971	0.617479979991913
1972	0.637780010700226
1973	0.634329974651337
1974	0.631200015544891
1975	0.639339983463287
1976	0.646179974079132
1977	0.672749996185303
1978	0.686160027980804
1979	0.692019999027252
1980	0.702750027179718
1981	0.725740015506744
1982	0.747169971466064
1983	0.726509988307953
1984	0.74848997592926
1985	0.741289973258972
1986	0.746800005435944
1987	0.756110012531281
1988	0.770470023155212
1989	0.777530014514923
1990	0.787699997425079
1991	0.799629986286163
1992	0.804520010948181
1993	0.809589982032776
1994	0.815299987792969
1995	0.807229995727539
1996	0.807420015335083
1997	0.813870012760162
1998	0.818790018558502
1999	0.838599979877472
2000	0.847400009632111
2001	0.854770004749298
2002	0.859319984912872
2003	0.868300020694733
2004	0.867929995059967
2005	0.890829980373383
2006	0.904399991035461
2007	0.910350024700165
2008	0.917320013046265
2009	0.925249993801117
2010	0.932879984378815
2011	0.928300023078918
2012	0.933759987354279
2013	0.939230024814606
2014	0.943610012531281
2015	0.953379988670349
2016	0.953670024871826
2017	0.95100998878479
2018	0.948589980602264
2019	0.95168000459671
2020	0.954509973526001