Year	Percent
1991	42.437
1992	43.964
1993	39.276
1994	42.642
1995	38.427
1996	34.683
1997	36.044
1998	39.133
1999	38.519
2000	38.09
2001	37.885
2002	34.323
2003	33.698
2004	32.649
2005	31.974
2006	32.292
2007	32.066
2008	32.749
2009	31.774
2010	31.435
2011	30.888
2012	29.694
2013	27.994
2014	26.861
2015	26.458
2016	25.86
2017	25.134
2018	24.512
2019	24.072
2020	23.547
2021	23.057
2022	22.626