Year	Percent
1991	48.294
1992	45.682
1993	49.301
1994	47.372
1995	56.591
1996	65.173
1997	63.784
1998	57.547
1999	57.158
2000	57.139
2001	57.352
2002	55.419
2003	52.844
2004	51.2
2005	50.522
2006	48.785
2007	49.185
2008	46.114
2009	40.647
2010	38.656
2011	38.614
2012	38.653
2013	44.893
2014	44.2
2015	41.282
2016	39.249
2017	39.158
2018	39.262
2019	39.796
2020	39.68
2021	39.495
2022	39.816