Year	gross (GPI)
1970	0.490260004997253
1971	0.486090004444122
1972	0.55146998167038
1973	0.551769971847534
1974	0.514970004558563
1975	0.537230014801025
1976	0.543429970741272
1977	0.608430027961731
1978	0.606620013713837
1979	0.605199992656708
1980	0.604709982872009
1981	0.694850027561188
1982	0.707409977912903
1983	0.605400025844574
1984	0.696850001811981
1985	0.692030012607574
1986	0.691039979457855
1987	0.691850006580353
1988	0.805660009384155
1989	0.81181001663208
1990	0.84442001581192
2005	1.04550004005432
2006	1.05589997768402
2007	1.07234001159668
2008	1.06190001964569
2009	1.04786002635956
2010	1.05883538722992
2011	1.01623558998108
2017	1.05962836742401
2018	1.06951701641083
2020	1.09301996231079
2021	1.01849806308746