Year	Percent
1996	45.8
1997	39.51
1998	37.79
1999	38.34
2000	37.04
2001	37.2
2002	37.9
2003	35.87
2004	32.71
2007	12.82
2009	16.85
2010	19.39
2011	18.46
2012	17.45
2013	17.17
2014	21.41
2015	17.17
2016	16.05
2017	15.59