Year	Percent
1991	42.897
1992	43.588
1993	45.365
1994	43.377
1995	43.696
1996	43.936
1997	42.862
1998	42.697
1999	41.675
2000	42.156
2001	41.339
2002	42.771
2003	41.451
2004	41.952
2005	41.79
2006	41.765
2007	40.983
2008	40.121
2009	39.542
2010	39.746
2011	38.836
2012	38.65
2013	39.457
2014	40.008
2015	40.014
2016	40.168
2017	40.215
2018	40.151
2019	40.043
2020	39.942
2021	39.871
2022	39.771