Year	gross (GPI)
1971	0.794839978218079
1972	0.796109974384308
1973	0.793060004711151
1974	0.790040016174316
1975	0.791999995708466
1976	0.805130004882813
1977	0.82108998298645
1978	0.851310014724731
1979	0.876470029354095
1980	0.889949977397919
1981	0.920369982719421
1982	0.942650020122528
1983	0.984660029411316
1984	0.991890013217926
1985	0.991100013256073
1986	0.978330016136169
1987	0.96451997756958
1988	0.956350028514862
1989	0.959689974784851
1990	0.975759983062744
1991	0.977810025215149
1992	0.98404997587204
1993	1.01286995410919
1994	0.962549984455109
1995	1.01366996765137
1996	1.02558994293213
1997	1.03509998321533
1998	1.03850996494293
1999	1.03793001174927
2000	1.05628001689911
2001	1.04296004772186
2002	1.01346004009247
2003	1.00152003765106
2004	0.982990026473999
2005	0.953939974308014
2006	0.946730017662048
2007	0.9340900182724
2010	0.965430021286011
2011	0.981060028076172
2012	0.970759987831116
2013	0.964380025863647
2014	0.942879974842072
2015	0.929759979248047
2016	0.936249971389771
2017	0.942969977855682
2018	0.948599994182587
2019	0.949490010738373
2020	0.954909980297089