Year	Percent
1991	47.288
1992	48.925
1993	46.25
1994	47.465
1995	41.886
1996	40.982
1997	41.136
1998	39.031
1999	38.413
2000	36.519
2001	37.005
2002	37.146
2003	36.76
2004	36.387
2005	35.731
2006	34.573
2007	34.01
2008	33.018
2009	33.832
2010	32.852
2011	33.057
2012	32.092
2013	32.46
2014	31.877
2015	31.605
2016	31.119
2017	31.118
2018	31.037
2019	31.007
2020	30.964
2021	30.9
2022	30.827