Year	gross (GPI)
1970	0.634360015392303
1971	0.639980018138886
1972	0.664659976959229
1974	0.694869995117188
1975	0.673280000686646
1976	0.703920006752014
1977	0.710380017757416
1978	0.716790020465851
1979	0.73566997051239
1980	0.756820023059845
1981	0.7498499751091
1982	0.748399972915649
1983	0.775590002536774
1984	0.777369976043701
1985	0.792010009288788
1986	0.831380009651184
1987	0.824150025844574
1988	0.790690004825592
1989	0.806789994239807
1990	0.800339996814728
1991	0.812820017337799
1992	0.781199991703033
1993	0.791190028190613
1994	0.922230005264282
1995	0.835529983043671
1996	0.858430027961731
1997	0.867680013179779
1998	0.891160011291504
1999	0.899290025234222
2000	0.927209973335266
2001	0.952660024166107
2002	0.974629998207092
2003	0.971199989318848
2004	0.977630019187927
2005	0.98497998714447
2006	0.994620025157928
2007	0.994360029697418
2008	0.99711000919342
2009	1.0001699924469
2010	1.00713002681732
2011	1.01091003417969
2012	1.01248002052307
2013	1.01718997955322
2014	1.01840114593506
2015	1.02101004123688
2016	1.03222000598907
2017	1.02788996696472