Year	Percent
1998	41.19
1999	38.26
2000	37.97
2001	37.9
2002	38.01
2003	36.74
2004	37.14
2005	36.36
2006	35.64
2007	36.19
2011	37.06
2012	37.6
2014	39.09
2016	40.06
2017	43.7