Year	gross (GPI)
1970	1.0760600566864
1971	1.05397999286652
1972	1.05288004875183
1973	1.06485998630524
1974	1.0938800573349
1975	1.08866000175476
1976	1.10821998119354
1977	1.08485996723175
1978	1.07903003692627
1979	1.0898300409317
1980	1.08345997333527
1981	1.09581005573273
1982	1.05343997478485
1983	1.05141997337341
1984	1.0448499917984
1985	1.05068004131317
1986	1.04624998569489
1989	1.04296004772186
1990	1.05184996128082
1991	1.01318001747131
1992	1.02599000930786
1993	1.05371999740601
1998	1.0409300327301
1999	1.03882002830505
2000	1.02253997325897
2002	1.01757001876831
2003	1.01298999786377
2004	1.01418995857239
2005	1.01298999786377
2006	1.02031004428864
2007	1.0255800485611
2008	1.02620005607605
2009	1.02921998500824
2010	1.03084003925323
2011	1.03058004379272
2012	1.03539001941681
2013	1.00962996482849
2014	1.00855994224548
2015	1.00653994083405
2016	1.00612998008728
2017	1.00381004810333
2018	1.00041997432709
2019	0.992429971694946
2020	0.99084997177124