Year	Percent
1991	38.457
1992	40.324
1993	41.563
1994	43.465
1995	40.859
1996	39.083
1997	41.446
1998	38.54
1999	38.046
2000	35.405
2001	35.732
2002	36.798
2003	36.884
2004	37.318
2005	35.386
2006	35.047
2007	35.172
2008	34.624
2009	35.14
2010	34.345
2011	34.687
2012	34.435
2013	33.698
2014	32.734
2015	32.907
2016	32.573
2017	32.489
2018	32.398
2019	32.364
2020	32.315
2021	32.242
2022	32.158