Year	gross (GPI)
1971	0.231790006160736
1972	0.244489997625351
1973	0.248750001192093
1974	0.251879990100861
1975	0.384180009365082
1980	0.355780005455017
1981	0.468169987201691
1982	0.481669992208481
1983	0.467310011386871
1985	0.539009988307953
1986	0.568989992141724
1988	0.59595000743866
1990	0.492190003395081
1993	0.430440008640289
1994	0.38111999630928
1995	0.409720003604889
1996	0.441900014877319
1997	0.446189999580383
1998	0.43503001332283
1999	0.483960002660751
2000	0.522159993648529
2001	0.583169996738434
2002	0.558600008487701
2003	0.559639990329742
2004	0.613590002059937
2005	0.701510012149811
2006	0.674300014972687
2007	0.724709987640381
2008	0.782959997653961
2009	0.807079970836639
2010	0.779009997844696
2011	0.751241564750671
2012	0.847226619720459
2013	0.897240877151489
2014	0.940495431423187
2015	0.968168020248413
2016	1.01265525817871
2017	1.06441509723663
2018	1.09108221530914
2019	1.13132202625275
2020	1.1490159034729
2021	1.138347864151