Year	Percent
1991	48.807
1992	46.202
1993	44.979
1994	44.23
1995	43.932
1996	41.855
1997	43.1
1998	40.923
1999	38.347
2000	38.289
2001	37.3
2002	31.21
2003	32.644
2004	32.624
2005	32.598
2006	33.768
2007	33.978
2008	34.538
2009	31.217
2010	35.027
2011	32.473
2012	33.422
2013	32.381
2014	34.934
2015	38.714
2016	38.649
2017	38.222
2018	38.195
2019	38.043
2020	37.462
2021	36.921
2022	36.387