Year	Percent
1991	26.181
1992	26.362
1993	26.519
1994	26.414
1995	26.428
1996	26.508
1997	26.755
1998	26.907
1999	27.417
2000	27.961
2001	27.078
2002	28.199
2003	27.214
2004	25.844
2005	27.15
2006	27.475
2007	29.38
2008	30.687
2009	30.845
2010	31.652
2011	32.929
2012	34.72
2013	36.806
2014	38.526
2015	39.448
2016	40.133
2017	40.536
2018	40.536
2019	40.516
2020	40.477
2021	40.424
2022	40.357