Year	gross (GPI)
1974	1.1679699420929
1975	1.03558003902435
1977	1.04458999633789
1978	0.839510023593903
1992	0.979719996452332
2007	0.983640015125275
2008	0.965020000934601
2009	0.990239977836609
2010	0.971769988536835
2011	0.964439988136292
2012	1.03903996944427
2014	0.97434002161026
2015	0.990040004253387
2017	0.979359984397888
2018	0.979240000247955