Year	Percent
1997	13.12
1998	12.99
1999	12.8
2000	15.39
2001	15.64
2002	12.78
2003	11.07
2004	9.78
2005	7.92
2006	5.36
2007	3.97
2008	5.2
2009	12.73
2010	16.71
2011	14.28
2012	12.55
2013	11
2014	9.92
2015	8.63
2016	7.39
2017	6.63
2018	5.55
2019	5.78
2020	7.4