Year	gross (GPI)
1971	0.65692001581192
1972	0.655340015888214
1973	0.654070019721985
1974	0.657079994678497
1975	0.657710015773773
1976	0.666329979896545
1977	0.674329996109009
1978	0.68519002199173
1979	0.696590006351471
1980	0.705190002918243
1981	0.717989981174469
1982	0.72996997833252
1983	0.746500015258789
1984	0.768090009689331
1985	0.78846001625061
1986	0.806129992008209
1987	0.819029986858368
1988	0.789120018482208
1989	0.835529983043671
1990	0.85004997253418
1991	0.841220021247864
1992	0.861779987812042
1993	0.868680000305176
1994	0.854709982872009
1995	0.888159990310669
1996	0.762960016727448
1997	0.878430008888245
1999	0.923250019550323
2000	0.931089997291565
2001	0.940599977970123
2002	0.948310017585754
2003	0.957329988479614
2004	0.967779994010925
2005	0.947350025177002
2006	0.950450003147125
2007	0.958100020885468
2009	0.967440009117126
2010	0.971019983291626
2011	0.954770028591156
2012	0.986760020256042
2013	0.991439998149872
2014	0.99712997674942
2016	1.00066995620728
2017	1.00267994403839
2018	1.0039199590683
2019	1.00809001922607