Year	Percent
1990	40.87
1991	41.42
1992	42.45
1993	42.13
1994	40.8
1995	41.8
1996	40.87
1997	41.21
1998	41.64
1999	40.28
2000	40.3
2001	38.53
2002	41.59
2003	38
2004	37.56
2005	37.97
2006	37.25
2007	37.67
2008	36.75
2009	36.56
2010	36.83
2011	36.15
2012	35.42
2013	35.18
2014	35.23
2015	35.54
2016	36.48
2017	31.37
2018	32.15
2019	32.66