Year	Percent
1991	44.491
1992	45.692
1993	43.58
1994	47.176
1995	50.031
1996	50.238
1997	49.569
1998	51.311
1999	50.86
2000	51.938
2001	51.701
2002	50.68
2003	44.333
2004	40.951
2005	41.139
2006	35.245
2007	35.47
2008	33.7
2009	31.423
2010	30.538
2011	30.837
2012	29.653
2013	32.14
2014	34.225
2015	38.506
2016	37.066
2017	36.604
2018	35.912
2019	35.167
2020	34.395
2021	33.629
2022	32.907