Year	Percent
1997	94.89058
1998	93.63504
1999	93.27126
2000	93.69434
2001	94.65581
2002	95.00716
2003	93.1922
2004	92.01606
2005	93.47264
2006	92.88124
2007	92.15603
2008	93.18945
2009	92.40065
2010	92.35118
2011	92.3367
2012	91.90058
2013	91.48162
2014	91.48721
2015	91.30544
2016	91.29426
2017	90.386