Year	Percent
1991	42.014
1992	40.017
1993	40.495
1994	38.957
1995	35.881
1996	35.332
1997	35.988
1998	35.855
1999	37.334
2000	35.9
2001	36.783
2002	37.094
2003	38.398
2004	38.682
2005	37.169
2006	38.809
2007	40.518
2008	41.042
2009	39.475
2010	38
2011	37.488
2012	37.163
2013	38.113
2014	36.846
2015	36.714
2016	37.542
2017	37.66
2018	37.552
2019	37.41
2020	37.213
2021	37.026
2022	36.84