Year	Percent
1991	64.029
1992	66.707
1993	66.556
1994	65.142
1995	64.152
1996	60.136
1997	58.756
1998	58.594
1999	56.289
2000	54.205
2001	52.193
2002	50.489
2003	49.048
2004	47.008
2005	44.704
2006	42.597
2007	37.68
2008	37.048
2009	35.053
2010	36.302
2011	38.723
2012	39.01
2013	37.965
2014	37.341
2015	36.7
2016	35.806
2017	35.398
2018	33.958
2019	32.799
2020	31.644
2021	30.366
2022	29.379