Year	Percent
1991	39.112
1992	39.166
1993	38.822
1994	38.433
1995	38.192
1996	38.758
1997	38.526
1998	38.931
1999	39.568
2000	38.995
2001	38.823
2002	38.476
2003	37.678
2004	38.958
2005	38.97
2006	39.417
2007	39.433
2008	39.383
2009	40.302
2010	39.778
2011	39.287
2012	40.257
2013	38.351
2014	37.326
2015	37.641
2016	37.673
2017	38.133
2018	38.968
2019	39.845
2020	40.615
2021	41.333
2022	42.116