Year	Percent
1991	55.129
1992	54.372
1993	52.784
1994	51.733
1995	50.774
1996	50.413
1997	49.164
1998	48.215
1999	47.649
2000	47.431
2001	46.372
2002	45.664
2003	45.424
2004	45.27
2005	44.309
2006	43.093
2007	42.059
2008	42.225
2009	43.115
2010	42.307
2011	41.745
2012	41.794
2013	41.72
2014	41.746
2015	41.542
2016	40.856
2017	40.753
2018	40.657
2019	40.56
2020	40.463
2021	40.368
2022	40.271