Year	Percent
1991	26.864
1992	24.53
1993	24.354
1994	26.36
1995	26.07
1996	26.732
1997	26.615
1998	25.795
1999	25.99
2000	26.327
2001	25.79
2002	24.658
2003	23.754
2004	23.385
2005	23.563
2006	23.068
2007	23.497
2008	23.993
2009	26.896
2010	30.721
2011	32.466
2012	36.48
2013	36.844
2014	36.939
2015	36.571
2016	36.532
2017	36.388
2018	36.507
2019	36.786
2020	37.112
2021	37.577
2022	37.99