Year	gross (GPI)
1972	0.814400017261505
1974	1.05545997619629
1975	1.17820000648499
1977	1.07884001731873
1978	0.728240013122559
1992	1.02424001693726
2000	0.923780024051666
2007	1.01375997066498
2008	0.989400029182434
2009	1.04480004310608
2010	1.05221998691559
2011	1.0130900144577
2012	1.15873003005981
2014	1.00592994689941
2015	1.02065002918243
2017	0.973399996757507
2018	0.962859988212585