Year	gross (GPI)
1971	0.804589986801147
1972	0.95754998922348
1977	0.904500007629395
1988	0.94989001750946
2003	0.990610003471375
2004	0.976230025291443
2005	0.98062002658844
2007	1.00574994087219
2008	0.99371999502182
2009	1.02790999412537
2010	0.999629974365234
2011	1.01201999187469
2012	1.01584994792938
2013	1.01865994930267
2014	1.01152002811432
2015	1.01635003089905
2016	1.02455997467041
2017	1.04054999351501