Year	Percent
1997	3.64928
1998	4.49653
1999	4.15696
2000	8.26249
2001	8.11331
2002	7.14361
2003	9.25977
2004	14.78992
2005	16.84579
2006	19.0818
2007	6.33932
2008	6.56006
2009	9.56104
2010	11.31799
2011	13.22623
2012	13.64973
2013	13.58378
2014	9.90056
2015	9.86445
2016	13.22142