Year	gross (GPI)
1970	0.156760007143021
1971	0.146139994263649
1972	0.132310003042221
1973	0.142179995775223
1974	0.138710007071495
1975	0.141039997339249
1976	0.151659995317459
1977	0.172279998660088
1978	0.179370000958443
1981	0.258639991283417
1982	0.445679992437363
1984	0.459390014410019
1985	0.454340010881424
1986	0.497509986162186
1988	0.490669995546341
1991	0.511690020561218
1993	0.381179988384247
1994	0.281430006027222
1995	0.375290006399155
2001	0
2003	0.350760012865067
2004	0.209610000252724
2005	0.3264200091362
2006	0.36353999376297
2007	0.375039994716644
2008	0.425500005483627
2009	0.481350004673004
2010	0.497850000858307
2011	0.554260015487671
2012	0.557489991188049
2013	0.552259981632233
2014	0.556400001049042
2015	0.557900011539459
2016	0.571280002593994
2017	0.568419992923737
2018	0.57098001241684