Year	gross (GPI)
1971	0.468019992113113
1972	0.533940017223358
1973	0.529929995536804
1974	0.461470007896423
1975	0.548600018024445
1981	0.722010016441345
1984	0.756120026111603
1985	0.899800002574921
1986	0.761370003223419
1987	0.799759984016418
1988	0.803529977798462
1989	0.809660017490387
1990	0.705160021781921
1991	0.730359971523285
1992	0.849579989910126
1993	0.878359973430634
1994	0.82820999622345
1998	0.860230028629303
1999	0.856060028076172
2000	0.857290029525757
2002	0.8230100274086
2003	0.823409974575043
2004	0.887019991874695
2007	0.899150013923645
2008	0.921720027923584
2011	0.846090018749237
2013	0.942019999027252
2014	0.931659996509552
2016	0.961900770664215
2017	0.957210004329681
2018	0.998350024223328