Year	Percent
1991	41.183
1992	40.614
1993	40.141
1994	40.129
1995	39.415
1996	38.541
1997	38.649
1998	36.999
1999	37.128
2000	40.196
2001	45.633
2002	44.785
2003	35.572
2004	35.561
2005	34.608
2006	36.555
2007	31.393
2008	31.107
2009	29.577
2010	29.652
2011	29.322
2012	28.159
2013	29.253
2014	30.463
2015	27.532
2016	27.004
2017	27.101
2018	26.451
2019	26.104
2020	25.754
2021	25.377
2022	24.969