Year	Percent
1991	46.984
1992	46.98717
1993	46.96233
1994	46.69184
1995	46.74905
1996	46.3515
1997	46.26381
1998	45.87467
1999	45.69737
2000	45.48219
2001	44.89312
2002	44.42827
2003	43.93317
2004	45.8633
2005	45.51327
2006	43.43189
2007	42.76866
2008	41.99689
2009	41.30774
2010	40.5794
2011	39.77988
2012	39.21961
2013	38.39737
2014	37.56647
2015	36.68389
2016	35.9565
2017	35.02417
2018	34.13783
2019	33.27374