Year	gross (GPI)
1970	0.393290013074875
1971	0.404379993677139
1972	0.423759996891022
1975	0.450549989938736
1976	0.437849998474121
1978	0.50722998380661
1979	0.517009973526001
1980	0.499779999256134
1999	0.728529989719391
2000	0.736270010471344
2011	0.88358998298645
2014	0.876460015773773
2015	0.863579988479614
2020	0.988730013370514