Year	gross (GPI)
1971	1.12613999843597
1972	1.1781200170517
1973	1.02893996238708
1974	1.0135600566864
1975	0.986779987812042
1976	1.00153005123138
1977	1.00494003295898
1978	1.00705003738403
1979	1.00889003276825
1980	1.01408004760742
1981	1.08195996284485
1982	1.02371001243591
1983	1.01581001281738
1984	1.00459003448486
1985	1.00128996372223
1986	0.984080016613007
1987	0.966840028762817
1988	0.953199982643127
1989	0.932299971580505
1990	0.947430014610291
1991	0.947749972343445
1992	0.932039976119995
1993	0.92645001411438
1997	0.930130004882813
1999	0.945969998836517
2000	0.968400001525879
2001	0.954240024089813
2002	0.968970000743866
2003	0.94990998506546
2004	0.948080003261566
2005	0.95550000667572
2006	0.920059978961945
2007	0.94964998960495
2012	0.967331290245056
2013	0.954678416252136
2014	0.955075204372406
2015	0.968159973621368
2016	0.967859983444214
2017	0.989459991455078
2018	1.01080000400543
2019	1.01810002326965
2020	1.02502000331879