Year	gross (GPI)
1971	0.9896399974823
1972	1.02177000045776
1974	1.03066003322601
1975	1.0557199716568
1976	1.03936004638672
1982	1.07624995708466
1984	1.04393005371094
1986	1.0550400018692
1987	1.06435000896454
1991	1.06560003757477
2000	1.06275999546051
2001	1.0223400592804
2002	1.00927996635437
2003	1.00863003730774
2004	0.998830020427704
2005	1.0135600566864
2007	1.02356004714966
2008	1.00982999801636
2009	0.994780004024506
2010	0.991900026798248
2011	0.97707998752594
2012	0.985759973526001
2013	0.974259972572327
2014	0.992709994316101
2015	0.997340023517609
2016	1.00497996807098
2017	0.991419970989227
2018	1.00522005558014