Year	gross (GPI)
1970	0.607630014419556
1971	0.554780006408691
1975	0.63221001625061
1986	0.792659997940063
1990	0.821280002593994
1991	0.816999971866608
1992	0.816860020160675
1993	0.818979978561401
1994	0.837909996509552
1999	0.882770001888275
2000	0.889880001544952
2002	0.900829970836639
2005	0.916949987411499
2006	0.921150028705597
2007	0.920300006866455
2010	0.942210018634796
2011	0.958140015602112
2012	0.973439991474152