Year	Percent
1991	33
1992	34.47
1993	36.6
1994	40
1995	38.8
1996	37.32
1997	35.98
1998	33.83
1999	32.99
2000	32.09
2001	31.65
2002	32.8
2003	33.01
2004	34.84
2005	34.98
2006	35.34
2007	35.83
2008	36.08
2009	34.49
2010	33.63
2011	34.53
2012	33.8
2013	32.45
2014	29.45
2015	28
2016	26.63
2017	27.28
2018	26.98
2019	27.04