Year	gross (GPI)
1970	0.285569995641708
1971	0.281399995088577
1972	0.283100008964539
1975	0.321799993515015
1976	0.309960007667542
1978	0.388790011405945
1979	0.375200003385544
1980	0.385509997606277
1999	0.653129994869232
2000	0.731090009212494
2011	0.813409984111786
2014	0.772669970989227
2015	0.769400000572205
2020	0.976689994335175