Year	Percent
1991	28.58
1992	27.408
1993	29.376
1994	29.454
1995	29.813
1996	31.035
1997	31.253
1998	31.805
1999	31.786
2000	32.767
2001	32.83
2002	32.757
2003	32.801
2004	32.341
2005	32.522
2006	31.79
2007	31.809
2008	31.03
2009	30.791
2010	29.12
2011	28.339
2012	28.523
2013	29.158
2014	28.693
2015	28.762
2016	28.237
2017	26.689
2018	26.012
2019	25.421
2020	24.89
2021	24.308
2022	23.861