Year	Percent
1991	53.692
1992	53.208
1993	51.584
1994	51.164
1995	51.1
1996	51.014
1997	49.309
1998	48.79
1999	47.762
2000	46.809
2001	46.441
2002	46.5
2003	46.384
2004	46.305
2005	45.815
2006	41.179
2007	40.427
2008	40.115
2009	39.944
2010	38.101
2011	37.449
2012	38.985
2013	41.835
2014	40.854
2015	38.704
2016	37.447
2017	36.741
2018	35.642
2019	34.295
2020	33.139
2021	32.13
2022	31.203