Year	Percent
1991	27.28149
1992	24.9775
1993	23.08178
1994	19.91075
1995	20.79965
1996	20.14557
1997	18.6409
1998	17.75198
1999	17.42995
2000	16.9612
2001	18.04634
2002	17.33197
2003	17.46133
2004	15.99296
2005	15.66561
2006	15.93689
2007	14.73827
2008	17.90658
2009	18.03845
2010	17.41828
2011	16.5495
2012	16.71278
2013	16.35813
2014	15.70297
2015	14.67321
2016	15.36169
2017	14.49424
2018	14.20714
2019	14.34122