Year	Percent
1991	24.778
1992	23.856
1993	23.037
1994	20.722
1995	20.416
1996	18.907
1997	16.508
1998	14.687
1999	12.438
2000	10.16
2001	8.655
2002	7.385
2003	7.376
2004	7.122
2005	7.816
2006	6.46
2007	5.877
2008	5.986
2009	5.602
2010	5.113
2011	5.007
2012	4.964
2013	4.711
2014	4.396
2015	4.529
2016	4.272
2017	3.772
2018	3.693
2019	3.595
2020	3.807
2021	4.043
2022	4.984