Year	Percent
1991	41.47
1992	39.494
1993	41.246
1994	40.576
1995	38.226
1996	38.218
1997	37.795
1998	36.839
1999	36.674
2000	36.625
2001	36.678
2002	36.452
2003	36.136
2004	35.952
2005	34.589
2006	34.41
2007	34.551
2008	34.275
2009	34.254
2010	34.483
2011	34.4
2012	34.407
2013	33.789
2014	33.33
2015	33.217
2016	34.231
2017	35.426
2018	35.223
2019	35.041
2020	38.109
2021	36.794
2022	34.424