Year	Percent
1991	83.23259
1992	82.97608
1993	83.37518
1994	82.96492
1995	82.88976
1996	82.78411
1997	82.52292
1998	82.21237
1999	82.21885
2000	82.23364
2001	81.70203
2002	81.28955
2003	80.62035
2004	79.65598
2005	78.88959
2006	78.74404
2007	78.47728
2008	78.21613
2009	77.89162
2010	77.15356
2011	77.04101
2012	76.49218
2013	76.11013
2014	75.65052
2015	75.37979
2016	75.60571
2017	75.63579
2018	75.38636
2019	75.06048