Year	gross (GPI)
1971	1.04853999614716
1972	1.09421002864838
1973	1.05680000782013
1974	1.00934994220734
1975	1.02040994167328
1976	1.07256996631622
1977	1.3554699420929
1978	0.979900002479553
1979	1.03816998004913
1980	1.04568994045258
1981	1.0382000207901
1982	1.04892003536224
1983	1.05656003952026
1984	1.05950999259949
1985	1.01963996887207
1999	0.950230002403259
2000	0.979470014572144
2001	1.01661002635956
2008	0.982559978961945
2009	0.976059973239899
2016	0.976180016994476
2017	0.971530020236969
2019	0.951640009880066
2020	0.976369976997375
2021	0.91839998960495