Year	Percent
1971	0.80406
1972	0.95747
1977	0.90408
1988	0.9489
2003	0.98969
2004	0.97644
2005	0.98054
2007	1.00453
2008	0.99224
2009	1.02529
2010	0.99671
2011	1.00917
2012	1.01132
2013	1.0134
2014	1.0063
2015	1.0114
2016	1.0195
2017	1.0349