Year	Percent
1991	45.48
1992	45.858
1993	51.963
1994	48.348
1995	50.993
1996	48.293
1997	43.503
1998	39.108
1999	34.664
2000	32.439
2001	34.196
2002	29.786
2003	26.869
2004	29.704
2005	32.595
2006	36.307
2007	40.955
2008	42.699
2009	42.304
2010	44.119
2011	44.061
2012	42.272
2013	41.488
2014	41.834
2015	40.659
2016	42.272
2017	42.583
2018	42.963
2019	43.123
2020	42.874
2021	41.905
2022	40.474