Year	gross (GPI)
1971	0.426259994506836
1972	0.42399999499321
1973	0.4341099858284
1974	0.449010014533997
1975	0.483000010251999
1976	0.502399981021881
1977	0.548500001430511
1978	0.580389976501465
1979	0.696799993515015
1980	0.737240016460419
1981	0.775340020656586
1982	0.789229989051819
1983	0.793259978294373
1984	0.778900027275085
1985	0.764540016651154
1986	0.759010016918182
1987	0.767960011959076
1988	0.790589988231659
1989	0.773729979991913
1993	0.786530017852783
1996	0.788800001144409
1999	0.778410017490387
2000	0.771420001983643
2003	0.812219977378845
2004	0.790799975395203
2007	0.813799977302551