Year	Percent
1996	31.64746
1997	31.99474
1998	28.63162
1999	29.38168
2000	30.3369
2001	35.74088
2002	37.02653
2003	46.35043
2004	37.7544
2005	31.51371
2006	32.04844
2007	27.20073
2008	29.96919
2009	21.95292
2010	14.39917
2011	10.20336
2012	14.5273
2013	18.37694
2014	21.98269
2015	23.79349
2016	26.75633