Year	Percent
1991	38.23
1992	37.844
1993	38.84
1994	37.561
1995	38.046
1996	36.921
1997	36.79
1998	35.415
1999	34.627
2000	33.234
2001	31.09
2002	30.951
2003	28.563
2004	28.541
2005	33.213
2006	35.277
2007	39.917
2008	44.295
2009	47.876
2010	51.928
2011	56.281
2012	61.002
2013	63.779
2014	66.149
2015	61.934
2016	61.262
2017	56.784
2018	55.899
2019	55.069
2020	54.202
2021	53.356
2022	52.501