Year	Percent
1991	38.531
1992	43.731
1993	44.892
1994	46.707
1995	43.533
1996	42.712
1997	41.034
1998	46.039
1999	44.407
2000	44.417
2001	45.772
2002	47.381
2003	48.972
2004	49.642
2005	50.521
2006	50.677
2007	50.98
2008	49.92
2009	51.45
2010	52.726
2011	52.743
2012	53.867
2013	54.475
2014	55.616
2015	56.38
2016	58.594
2017	58.067
2018	57.569
2019	57.858
2020	58.05
2021	58.025
2022	58.031