Year	Percent
1991	83.327
1992	83.12
1993	83.478
1994	83.206
1995	83.228
1996	82.58
1997	81.798
1998	83.139
1999	80.19
2000	74.92
2001	69.696
2002	70.563
2003	71.204
2004	71.204
2005	72.165
2006	72.239
2007	73.127
2008	75.057
2009	64.884
2010	55.379
2011	44.483
2012	32.87
2013	31.691
2014	30.051
2015	28.318
2016	26.934
2017	26.193
2018	25.224
2019	24.216
2020	23.256
2021	22.276
2022	21.464