Year	gross (GPI)
1970	0.169190004467964
1971	0.164529994130135
1972	0.168249994516373
1973	0.175960004329681
1974	0.174669995903969
1975	0.18308000266552
1976	0.189060002565384
1977	0.198269993066788
1978	0.204669997096062
1980	0.229980006814003
1981	0.237020000815392
1982	0.502849996089935
1984	0.474640011787415
1985	0.485430002212524
1986	0.543280005455017
1988	0.501929998397827
1989	0.528739988803864
1990	0.548500001430511
1991	0.547879993915558
1993	0.353069990873337
1994	0.505800008773804
1995	0.515049993991852
1999	0.0848999992012978
2000	0
2001	0
2002	0.456930011510849
2003	0.562200009822845
2004	0.432819992303848
2005	0.583339989185333
2006	0.623570024967194
2007	0.613789975643158
2008	0.636420011520386
2009	0.657500028610229
2010	0.679809987545013
2011	0.712580025196075
2012	0.72026002407074
2013	0.702859997749329
2014	0.698249995708466
2015	0.68080997467041
2016	0.679369986057281
2017	0.676169991493225
2018	0.666909992694855
2019	0.671689987182617