Year	Percent
1989	44.39079
1990	40.24991
1991	42.5262
1992	42.92364
1993	41.10362
1994	39.06413
1995	40.86069
1996	40.73086
1997	55.70189
1998	43.5732
1999	40.52633
2000	42.2317
2001	41.83643
2002	42.05294
2003	41.93378
2004	44.06011
2005	43.39041
2006	38.14387
2007	41.66991
2008	44.10809
2009	45.69888
2010	43.57148
2011	41.77419
2012	40.15232
2013	42.49215
2014	44.15768
2015	44.16918
2016	42.4771
2017	41.52783