Year	gross (GPI)
1971	0.479600012302399
1972	0.487610012292862
1973	0.49932000041008
1974	0.521679997444153
1975	0.508629977703094
1976	0.553709983825684
1977	0.542490005493164
1978	0.537660002708435
1979	0.54926997423172
1980	0.583819985389709
1981	0.574270009994507
1982	0.569980025291443
1983	0.534950017929077
1984	0.565519988536835
1985	0.56470000743866
1986	0.636579990386963
1987	0.617560029029846
1988	0.614409983158112
1989	0.619170010089874
1990	0.635380029678345
1991	0.655589997768402
1992	0.673389971256256
2001	0.695919990539551
2002	0.680909991264343
2003	0.698140025138855
2004	0.674600005149841
2005	0.700540006160736
2006	0.700569987297058
2007	0.710799992084503
2008	0.719519972801209
2009	0.723510026931763
2010	0.725679993629456
2011	0.740239977836609
2012	0.758469998836517
2016	0.780099987983704
2017	0.765718936920166