Year	Percent
1991	45.256
1992	43.521
1993	44.977
1994	44.352
1995	42.342
1996	42.108
1997	41.373
1998	40.33
1999	40.144
2000	39.754
2001	39.72
2002	39.524
2003	39.252
2004	39.087
2005	38.106
2006	37.366
2007	37.337
2008	37.308
2009	37.122
2010	37.093
2011	37.108
2012	37.167
2013	36.73
2014	36.309
2015	36.368
2016	36.835
2017	37.73
2018	37.512
2019	37.318
2020	40.58
2021	39.215
2022	36.667