Year	Percent
1991	40.428
1992	42.176
1993	41.54
1994	41.002
1995	40.477
1996	40.725
1997	40.83
1998	40.24
1999	39.639
2000	39.038
2001	38.455
2002	37.881
2003	37.314
2004	37.781
2005	38.216
2006	38.625
2007	39.01
2008	39.384
2009	39.758
2010	40.137
2011	40.518
2012	40.891
2013	39.9
2014	37.313
2015	37.027
2016	36.879
2017	37.244
2018	37.6
2019	37.953
2020	38.298
2021	38.632
2022	39.154