Year	Percent
1991	24.39789
1992	24.18903
1993	23.96453
1994	23.11155
1995	27.15011
1996	28.68059
1997	29.90978
1998	25.02052
1999	27.47226
2000	26.03753
2001	24.66915
2002	23.33746
2003	21.98654
2004	20.76777
2005	19.55896
2006	19.41846
2007	19.30587
2008	19.13404
2009	19.02203
2010	18.88752
2011	18.77938
2012	18.61734
2013	18.45898
2014	18.24787
2015	18.08143
2016	18.56241
2017	17.41793
2018	17.00613
2019	16.8125