Year	Percent
1990	12.35
1991	13.26
1992	13.82
1993	14.76
1994	14.64
1995	14.49
1996	14.49
1997	14.12
1998	15.22
1999	15.82
2000	14.91
2001	15.57
2002	16.04
2003	15.66
2004	15.87
2005	17.85
2006	18.64
2007	19.64
2008	20.7
2009	21.64
2010	22.41
2011	23.4
2012	24.16
2013	24.75
2014	25.23
2015	25.64
2016	26.17
2017	26.69
2018	28.11
2019	28.01