Year	gross (GPI)
1970	0.953079998493195
1971	0.952530026435852
1972	0.958980023860931
1973	0.965780019760132
1974	0.970860004425049
1975	0.965520024299622
1976	0.960810005664825
1977	0.962970018386841
1978	0.96382999420166
1979	0.965849995613098
1980	0.969290018081665
1981	0.965430021286011
1982	0.962220013141632
1983	0.963460028171539
1984	0.962329983711243
1985	0.969860017299652
1986	0.964569985866547
1987	0.971509993076324
1988	0.97325998544693
1989	0.975430011749268
1990	0.975889980792999
1991	0.973969995975494
1992	0.977840006351471
1993	0.974929988384247
1994	0.972249984741211
1995	0.965960025787354
1996	0.967170000076294
1997	0.963429987430573
1998	0.960780024528503
1999	0.958989977836609
2000	0.958779990673065
2001	0.959829986095428
2002	0.957769989967346
2003	0.961189985275269
2004	0.959200024604797
2005	0.961700022220612
2006	0.969980001449585
2007	0.974420011043549
2008	0.981700003147125
2009	0.984109997749329
2010	0.983039975166321
2011	0.980740010738373
2012	0.99261999130249
2013	0.99769002199173
2014	0.998870015144348
2015	0.998570024967194
2016	0.999469995498657
2017	1.00446999073029
2018	1.00736999511719
2019	1.00862002372742
2020	1.00821995735168