Year	Percent
1991	30.435
1992	28.186
1993	28.152
1994	28.156
1995	28.638
1996	28.795
1997	30.084
1998	29.051
1999	29.049
2000	29.215
2001	31.23
2002	30.658
2003	30.583
2004	31.262
2005	28.613
2006	29.366
2007	27.016
2008	27.177
2009	27.35
2010	23.998
2011	20.97
2012	21.653
2013	24.026
2014	22.75
2015	22.427
2016	21.788
2017	21.79
2018	21.759
2019	21.729
2020	21.701
2021	21.672
2022	21.645