Year	Percent
1991	43.24979
1992	43.19807
1993	43.19852
1994	43.31271
1995	43.15821
1996	42.99589
1997	42.99255
1998	42.7011
1999	42.74919
2000	42.28693
2001	41.82456
2002	41.30802
2003	41.00358
2004	40.60944
2005	39.96862
2006	39.39188
2007	39.2519
2008	38.70991
2009	37.95069
2010	37.24127
2011	36.70582
2012	36.16576
2013	35.62042
2014	34.8816
2015	34.35274
2016	34.22074
2017	34.06497
2018	33.73514
2019	33.53003