Year	Percent
1991	43.652
1992	43.287
1993	43.435
1994	43.018
1995	42.775
1996	42.761
1997	42.532
1998	42.202
1999	41.384
2000	41.202
2001	40.785
2002	40.075
2003	40.136
2004	40.451
2005	40.958
2006	40.335
2007	40.128
2008	39.26
2009	38.596
2010	38.025
2011	39.216
2012	39.203
2013	39.594
2014	39.912
2015	39.709
2016	39.083
2017	38.495
2018	37.904
2019	37.457
2020	37.223
2021	37.099
2022	37.117