Year	Percent
1991	24.919
1992	24.789
1993	22.771
1994	21.493
1995	21.085
1996	20.259
1997	18.986
1998	19.709
1999	17.682
2000	18.635
2001	18.061
2002	15.547
2003	18.419
2004	17.544
2005	17.227
2006	16.349
2007	15.49
2008	17.409
2009	15.257
2010	13.586
2011	13.932
2012	14.014
2013	13.525
2014	12.852
2015	12.731
2016	13.337
2017	13.129
2018	12.799
2019	12.472
2020	12.156
2021	11.869
2022	11.599