Year	Percent
1991	31.259
1992	27.066
1993	29.327
1994	32.449
1995	32.361
1996	30.978
1997	35.115
1998	34.506
1999	35.648
2000	36.068
2001	36.288
2002	36.471
2003	35.678
2004	35.297
2005	35.606
2006	33.129
2007	33.24
2008	31.247
2009	30.149
2010	30.119
2011	30.105
2012	29.933
2013	29.669
2014	29.477
2015	28.971
2016	29.372
2017	28.888
2018	28.905
2019	28.896
2020	28.896
2021	28.897
2022	28.898