Year	Percent
1997	92.37778
1998	92.0259
1999	91.98923
2000	90.68632
2001	90.00321
2002	91.17466
2003	91.359
2004	91.29444
2005	89.7362
2006	89.59491
2007	88.95267
2011	88.95783