Year	Percent
1991	40.096
1992	42.601
1993	47.101
1994	50.603
1995	54.096
1996	56.282
1997	53.531
1998	51.102
1999	50.589
2000	49.4
2001	49.288
2002	49.423
2003	43.431
2004	39.068
2005	39.342
2006	36.924
2007	34.816
2008	34.322
2009	31.4
2010	31.289
2011	30.548
2012	30.445
2013	30.85
2014	29.624
2015	27.544
2016	26.124
2017	26.024
2018	25.385
2019	24.829
2020	24.135
2021	23.574
2022	22.886