Year	Percent
1990	27.8
1991	27.82
1992	27.79
1993	27.59
1994	27.67
1995	27.32
1996	27.14
1997	27.28
1998	27.17
1999	27
2000	27.05
2001	27
2002	26.85
2003	26.51
2004	26.24
2005	25.85
2006	25.27
2007	25.28
2008	25.24
2009	25.18
2010	25.04
2011	24.92
2012	24.77
2013	24.65
2014	24.52
2015	24.36
2016	24.41
2017	24.38
2018	24.37
2019	24.23