Year	Percent
1991	22.324
1992	22.657
1993	22.646
1994	22.098
1995	21.35
1996	20.862
1997	21.497
1998	21.261
1999	20.842
2000	20.768
2001	20.471
2002	20.482
2003	20.718
2004	20.46
2005	20.843
2006	22.43
2007	22.82
2008	23.931
2009	24.471
2010	25.068
2011	25.131
2012	24.608
2013	21.369
2014	21.85
2015	21.623
2016	21.946
2017	22.011
2018	21.992
2019	22.099
2020	22.139
2021	22.236
2022	22.349