Year	Percent
1991	31.695
1992	32.049
1993	31.585
1994	32.148
1995	31.862
1996	32.184
1997	32.226
1998	29.644
1999	29.564
2000	29.965
2001	29.702
2002	28.339
2003	28.95
2004	28.48
2005	28.979
2006	29.583
2007	29.861
2008	29.712
2009	29.634
2010	29.809
2011	29.953
2012	30.039
2013	29.737
2014	29.404
2015	29.038
2016	29.691
2017	27.674
2018	27.834
2019	28.028
2020	28.243
2021	28.427
2022	28.568