Year	Percent
1991	33.679
1992	33.573
1993	33.56
1994	33.631
1995	33.862
1996	34.084
1997	34.212
1998	34.093
1999	34.082
2000	34.041
2001	33.964
2002	33.809
2003	33.991
2004	34.395
2005	35.019
2006	35.444
2007	35.877
2008	36.387
2009	36.578
2010	37.278
2011	38.16
2012	38.54
2013	38.786
2014	39.05
2015	39.173
2016	39.732
2017	39.926
2018	40.283
2019	40.703
2020	41.158
2021	41.596
2022	41.994