Year	Percent
1991	26.117
1992	27.307
1993	26.541
1994	26.347
1995	28.316
1996	27.465
1997	25.262
1998	23.883
1999	23.833
2000	22.922
2001	21.553
2002	20.944
2003	19.396
2004	18.038
2005	17.425
2006	16.27
2007	15.211
2008	14.153
2009	14.006
2010	13.523
2011	12.706
2012	12.713
2013	12.26
2014	12.314
2015	12.459
2016	12.822
2017	12.988
2018	12.722
2019	12.43
2020	11.938
2021	11.627
2022	11.31