Year	Percent
1991	31.573
1992	30.047
1993	24.183
1994	28.616
1995	28.56
1996	28.617
1997	26.431
1998	27.11
1999	27.56
2000	24.676
2001	24.87
2002	24.993
2003	23.616
2004	20.85
2005	20.737
2006	20.98
2007	21.027
2008	21.626
2009	22.308
2010	23.994
2011	25.501
2012	26.199
2013	26.961
2014	26.7
2015	27.54
2016	28.107
2017	27.706
2018	27.727
2019	27.574
2020	27.575
2021	27.542
2022	27.485