Year	Percent
1991	23.72802
1992	23.57125
1993	23.35748
1994	23.0841
1995	22.82858
1996	22.61703
1997	22.29717
1998	22.17924
1999	22.35153
2000	22.42907
2001	22.19667
2002	21.92707
2003	21.55331
2004	21.02974
2005	20.65716
2006	20.01221
2007	19.36779
2008	19.03134
2009	18.61675
2010	18.37931
2011	17.81126
2012	17.40779
2013	16.60019
2014	16.22945
2015	16.00625
2016	16.00635
2017	16.53373
2018	16.70852
2019	15.81105