Year	Percent
1991	29.134
1992	29.22
1993	29.219
1994	29.176
1995	29.08
1996	29.184
1997	29.207
1998	28.728
1999	28.217
2000	27.778
2001	27.376
2002	27.088
2003	26.672
2004	26.314
2005	27.882
2006	29.487
2007	30.719
2008	33.516
2009	36.465
2010	40.313
2011	42.686
2012	43.882
2013	45.051
2014	49.197
2015	42.521
2016	42.403
2017	42.707
2018	42.996
2019	43.28
2020	43.664
2021	44.061
2022	44.459