Year	Percent
1990	27.71
1991	27.69
1992	27.52
1993	27.4
1994	27.33
1995	27.21
1996	27.12
1997	26.98
1998	26.86
1999	26.75
2000	26.66
2001	26.48
2002	24.99
2003	24.19
2004	25.62
2005	25.78
2006	24.84
2007	24.1
2008	23.46
2009	23.39
2010	21.71
2011	24.52
2012	26.82
2013	25.45
2014	25.54
2015	26.46
2016	27.98
2017	28.52
2018	27.79
2019	30.67