Year	gross (GPI)
1971	0.230279996991158
1972	0.206450000405312
1973	0.195230007171631
1976	0.217199996113777
1977	0.215639993548393
1978	0.264739990234375
1979	0.267439991235733
1980	0.343180000782013
1981	0.353610008955002
1982	0.352019995450974
1986	0.363979995250702
1987	0.399659991264343
1988	0.380329996347427
1989	0.4064100086689
1990	0.398680001497269
1991	0.411579996347427
1992	0.411909997463226
2001	0.531870007514954
2009	0.565039992332459
2011	0.558480024337769
2012	0.521510004997253
2016	0.649670004844666
2017	0.672689974308014