Year	Percent
1991	29.374
1992	30.124
1993	30.337
1994	31.329
1995	28.887
1996	29.495
1997	31.906
1998	32.369
1999	33.246
2000	33.933
2001	34.339
2002	35.257
2003	36.396
2004	37.313
2005	38.166
2006	39.16
2007	39.778
2008	40.079
2009	42.027
2010	40.436
2011	42.847
2012	42.611
2013	43.824
2014	45.106
2015	46.529
2016	49.076
2017	48.957
2018	49.069
2019	49.51
2020	50.046
2021	50.643
2022	51.299