Year	Percent
1991	11.14
1996	9.68
1997	9.71
1998	11.39
1999	13.56
2000	16.06
2001	15.82
2002	15.05
2003	13.92
2004	13.66
2005	12.6
2006	11.13
2007	9.91
2008	8.53
2009	9.2
2010	11.62
2011	13.68
2012	15.93
2013	17.25
2014	17.29
2015	16.18
2016	13.1
2017	11.21
2018	8.43
2019	6.62
2020	7.51