Year	Percent
1991	36.596
1992	34.222
1993	33.863
1994	28.105
1995	30.202
1996	25.694
1997	25.222
1998	30.611
1999	27.877
2000	26.349
2001	27.513
2002	26.348
2003	25.458
2004	24.596
2005	26.747
2006	27.863
2007	27.636
2008	26.999
2009	23.38
2010	20.254
2011	19.82
2012	20.39
2013	20.617
2014	22.905
2015	26.514
2016	28.394
2017	31.345
2018	30.481
2019	29.907
2020	29.638
2021	29.355
2022	29.082