Year	Percent
1991	43.804
1992	40.734
1993	39.371
1994	36.891
1995	35.304
1996	34.286
1997	34.963
1998	35.3
1999	32.553
2000	32.787
2001	32.511
2002	34.842
2003	33.947
2004	36.281
2005	37.032
2006	39.653
2007	41.062
2008	41.869
2009	36.907
2010	33.396
2011	33.35
2012	34.616
2013	35.192
2014	33.61
2015	34.03
2016	35.192
2017	35.055
2018	34.88
2019	34.698
2020	34.524
2021	34.356
2022	34.195