Year	gross (GPI)
1970	0.575280010700226
1971	0.574620008468628
1972	0.583180010318756
1973	0.593259990215302
1974	0.600929975509644
1975	0.611270010471344
1976	0.625230014324188
1977	0.639680027961731
1978	0.651750028133392
1979	0.67425000667572
1980	0.687780022621155
1981	0.701839983463287
1982	0.713389992713928
1983	0.725600004196167
1984	0.739049971103668
1985	0.751879990100861
1986	0.762380003929138
1987	0.769309997558594
1988	0.773069977760315
1989	0.786210000514984
1990	0.799260020256042
1991	0.810959994792938
1992	0.825389981269836
1993	0.834710001945496
1994	0.838949978351593
1995	0.853269994258881
1996	0.841679990291595
1997	0.864979982376099
1998	0.875
1999	0.886319994926453
2000	0.894999980926514
2001	0.902059972286224
2002	0.908460021018982
2003	0.91500997543335
2004	0.920029997825623
2005	0.924099981784821
2006	0.928870022296906
2007	0.937849998474121
2008	0.935660004615784
2009	0.935720026493073
2010	0.936739981174469
2011	0.935639977455139
2012	0.940129995346069
2013	0.945640027523041
2014	0.95253998041153
2015	0.954840004444122
2016	0.958580017089844
2017	0.958440005779266
2018	0.961239993572235
2019	0.964139997959137
2020	0.967329978942871