Year	Percent
1991	33.455
1992	33.843
1993	30.441
1994	29.719
1995	27.569
1996	24.36
1997	24.855
1998	29.444
1999	30.587
2000	28.492
2001	27.009
2002	26.156
2003	23.752
2004	20.365
2005	19.156
2006	18.322
2007	17.288
2008	16.535
2009	15.592
2010	15.892
2011	15.729
2012	16.768
2013	16.964
2014	20.547
2015	23.289
2016	24.907
2017	24.583
2018	24.208
2019	23.554
2020	22.943
2021	22.397
2022	21.925