Year	gross (GPI)
1970	0.537209987640381
1971	0.536300003528595
1972	0.544059991836548
1973	0.552619993686676
1974	0.563160002231598
1975	0.563950002193451
1976	0.580099999904633
1977	0.595459997653961
1978	0.603320002555847
1979	0.614970028400421
1980	0.622870028018951
1981	0.636740028858185
1982	0.650309979915619
1983	0.664370000362396
1984	0.674639999866486
1985	0.68572998046875
1986	0.695330023765564
1987	0.706160008907318
1988	0.718400001525879
1989	0.728690028190613
1990	0.751160025596619
1991	0.766600012779236
1992	0.786989986896515
1993	0.798370003700256
1994	0.803669989109039
1995	0.823050022125244
1996	0.828429996967316
1997	0.839619994163513
1998	0.856769979000092
1999	0.873449981212616
2000	0.882770001888275
2001	0.889410018920898
2002	0.901870012283325
2003	0.912029981613159
2004	0.91430002450943
2005	0.925249993801117
2006	0.932539999485016
2007	0.937059998512268
2008	0.93502002954483
2009	0.931159973144531
2010	0.932780027389526
2011	0.938579976558685
2012	0.940259993076324
2013	0.942879974842072
2014	0.945800006389618
2015	0.951059997081757
2016	0.944620013237
2017	0.944559991359711
2018	0.952910006046295
2019	0.952509999275208
2020	0.958819985389709