Year	gross (GPI)
1971	1.00853002071381
1972	1.01311004161835
1973	1.01304996013641
1974	1.01231002807617
1975	1.01195001602173
1976	1.01119005680084
1977	1.00969004631042
1978	1.00909996032715
1979	1.00864005088806
1980	1.00908994674683
1981	1.01026999950409
1982	1.0110000371933
1983	1.01173996925354
1984	1.01180005073547
1985	1.00959002971649
1986	1.01048004627228
1987	1.01075994968414
1988	1.01196002960205
1989	1.01333999633789
1990	1.01502001285553
1991	1.01102995872498
1992	1.01159000396729
1993	1.01453995704651
1994	1.01110005378723
1995	1.01074004173279
1998	1.01108002662659
1999	1.01084995269775
2013	1.00559997558594
2014	1.00538003444672
2015	1.0045599937439
2016	1.00527000427246
2017	1.00452995300293
2018	1.00345003604889
2019	1.0034099817276