Year	gross (GPI)
1972	1.22180998325348
1973	1.09404003620148
1974	1.12074995040894
1975	1.10640001296997
1976	1.03134000301361
1977	1.08472001552582
1978	1.0655699968338
1979	1.08864998817444
1980	1.05897998809814
1981	1.00686001777649
1999	0.915740013122559
2000	1.0273699760437
2001	0.98198002576828
2002	0.991940021514893
2004	0.959119975566864
2005	0.955209970474243
2006	0.942139983177185
2007	0.950360000133514
2008	0.937870025634766
2011	1.0401200056076
2012	1.03064000606537
2013	1.01950001716614
2014	1.00307357311249
2015	0.968655705451965
2016	0.974661767482758
2017	0.947557389736176
2018	0.966859996318817