Year	gross (GPI)
1970	0.929489970207214
1972	0.962859988212585
1973	0.953700006008148
1974	0.981149971485138
1975	0.99251002073288
1976	1.00112998485565
1977	1.00133001804352
1978	1.0067800283432
1980	1.01370000839233
1981	1.01268005371094
1983	1.01312005519867
1984	1.00171005725861
1985	1.00126004219055
1986	1.00404000282288
1987	1.00668001174927
1991	0.983810007572174
1992	0.998250007629395
1998	1.02600002288818
1999	1.04311001300812
2000	1.03109002113342
2001	1.0278400182724
2002	1.03849005699158
2003	1.0307400226593
2004	1.02281999588013
2006	1.03922998905182
2007	1.04455995559692
2008	1.03134000301361
2009	1.03707003593445
2011	1.03643000125885
2012	1.04857003688812
2014	1.02251660823822
2015	1.02075028419495
2016	1.02326023578644
2018	1.01970732212067
2020	1.01709544658661
2021	1.0168958902359