Year	Percent
1991	31.98
1992	32.855
1993	33.528
1994	33.129
1995	32.328
1996	32.159
1997	31.553
1998	30.366
1999	30.463
2000	29.678
2001	29.625
2002	29.086
2003	28.736
2004	29.052
2005	28.65
2006	29.816
2007	30.685
2008	30.655
2009	31.212
2010	31.696
2011	32.418
2012	32.886
2013	33.44
2014	33.719
2015	34.01
2016	34.335
2017	34.347
2018	34.525
2019	34.69
2020	35.461
2021	36.002
2022	36.215