Year	Percent
1991	37.596
1992	41.56
1993	42.987
1994	40.078
1995	39.735
1996	37.885
1997	35.266
1998	35.508
1999	33.778
2000	33.155
2001	31.977
2002	30.994
2003	29.85
2004	29.685
2005	28.897
2006	27.806
2007	26.819
2008	26.638
2009	29.146
2010	28.441
2011	29.14
2012	29.942
2013	30.569
2014	32.682
2015	34.054
2016	35.608
2017	34.21
2018	33.293
2019	32.334
2020	31.322
2021	30.281
2022	29.255