Year	Percent
1991	54.505
1992	49.251
1993	48.198
1994	47.76
1995	48.16
1996	47.179
1997	45.888
1998	44.25
1999	43.745
2000	44.636
2001	44.491
2002	44.741
2003	46.367
2004	43.6
2005	44.151
2006	43.539
2007	43.554
2008	42.97
2009	42.7
2010	42.315
2011	41.956
2012	41.112
2013	40.985
2014	41.138
2015	40.491
2016	39.633
2017	39.534
2018	39.464
2019	39.39
2020	39.308
2021	39.221
2022	39.131