Year	Percent
1997	25.79
1998	25.24
1999	25.46
2000	28.56
2001	31.58
2002	20.44
2003	26.92
2004	20.26
2005	15.76
2006	9.98
2007	8.4
2008	13.35
2009	29.55
2010	35.71
2011	32.58
2012	26.67
2013	21.89
2014	19.25
2015	16.3
2016	14.45
2017	13.26
2018	11.11
2019	11.85
2020	19.56