Year	Percent
1990	76.75
1991	77.82
1992	79.56
1993	81.37
1994	83.61
1995	84.29
1996	83.86
1997	83.14
1998	83.07
1999	82.85
2000	82.43
2001	82.01
2002	82.1
2003	82.6
2004	82.98
2005	84.25
2006	85.18
2007	83.98
2008	82.61
2009	81.02
2010	81.72
2011	82.3
2012	82.21
2013	78.52
2014	79.14
2015	78.68
2016	77.63
2017	76.01
2018	74.32
2019	74.19