Year	Percent
1991	15.90828
1992	15.70503
1993	15.66224
1994	15.60878
1995	15.26201
1996	15.07534
1997	17.7564
1998	20.72994
1999	20.30981
2000	19.95538
2001	20.48193
2002	20.80517
2003	21.18662
2004	21.92104
2005	22.59403
2006	23.14401
2007	23.72263
2008	24.37096
2009	25.08911
2010	24.58516
2011	24.0507
2012	23.56752
2013	22.84051
2014	22.26998
2015	21.89087
2016	21.34899
2017	20.86857
2018	20.35175
2019	19.87646