Year	Percent
1991	43.594
1992	42.412
1993	42.106
1994	40.812
1995	40.457
1996	39.26
1997	38.74
1998	37.232
1999	35.932
2000	36.048
2001	36.11
2002	36.241
2003	35.229
2004	35.336
2005	34.11
2006	30.634
2007	30.975
2008	29.11
2009	27.379
2010	28.567
2011	27.341
2012	26.963
2013	25.462
2014	23.33
2015	22.926
2016	22.521
2017	21.164
2018	19.865
2019	19.064
2020	18.225
2021	17.432
2022	16.788