Year	gross (GPI)
1970	0.265780001878738
1971	0.241459995508194
1972	0.303050011396408
1973	0.307179987430573
1975	0.274809986352921
1979	0.387769997119904
1987	0.31674000620842
1999	0.230509996414185
2000	0.533079981803894
2010	0.516799986362457
2012	0.609510004520416