Year	Percent
1988	74.87828
1989	74.42032
1991	76.33512
1992	79.86423
1993	79.30861
1996	75.96647
1997	76.46254
1999	77.05962
2000	79.07043
2001	80.34598
2002	87.44486
2003	85.73657
2004	85.57698
2005	87.00412
2006	90.85138
2007	93.61972
2008	92.33525
2009	92.2524
2010	91.23058
2011	92.3787
2012	93.76349
2013	93.824
2014	95.34503
2015	94.57464
2016	91.62609