Year	Percent
1996	61.55
1997	55.87
1998	53.17
1999	54.15
2000	53.06
2001	52.94
2002	52.59
2003	50.34
2004	47.23
2007	13.93
2009	22.21
2010	26.2
2011	24.84
2012	23.12
2013	22.6
2014	26.54
2015	23.27
2016	22.05
2017	21.43