Year	Percent
1972	0.98659
1973	0.97894
1974	0.9744
1975	0.97
1978	0.98522
1979	0.99384
1980	0.98892
1981	0.99315
1982	0.99634
1983	1.00465
1984	0.99444
1985	0.99285
1986	1.00176
1987	1.00278
1988	1.01357
1989	1.03314
1990	1.04739
1991	1.0612
1992	1.07063
1993	1.05446
1994	1.04078
1995	1.041
1996	0.99423
1997	1.01605
1999	0.99502
2000	0.98857
2001	0.99349
2002	0.97201
2003	0.97131
2004	0.98926
2005	0.99382
2006	0.99957
2007	0.99345
2008	0.99414
2009	0.99576
2010	0.99465
2011	0.99598
2012	1.0036
2013	0.99869
2014	0.9891
2015	0.99124