Year	Percent
1991	67.258
1992	63.274
1993	60.408
1994	61.715
1995	62.584
1996	62.262
1997	61.906
1998	61.765
1999	58.813
2000	54.518
2001	52.159
2002	47.915
2003	52.268
2004	50.093
2005	48.622
2006	48.014
2007	47.065
2008	43.449
2009	44.331
2010	41.781
2011	35.748
2012	35.291
2013	34.874
2014	34.674
2015	34.317
2016	34.347
2017	34.209
2018	34.296
2019	34.309
2020	34.335
2021	34.194
2022	33.935