Year	gross (GPI)
1971	1.01286995410919
1972	1.01446998119354
1973	0.998399972915649
1974	1.04121994972229
1975	1.01698005199432
1976	1.03539001941681
1977	1.03006994724274
1978	1.09212005138397
1979	1.08414995670319
1980	1.09565997123718
1981	1.0558500289917
1982	1.05260002613068
1983	1.01988995075226
1984	1.01575994491577
1985	0.987469971179962
1997	0.949050009250641
1999	0.730920016765594
2000	0.993160009384155
2001	0.996569991111755
2008	1.02646994590759
2009	1.01703000068665
2016	0.993939995765686
2017	1.00339996814728
2019	1.02162003517151
2020	1.09308004379272
2021	1.0670599937439