Year	Percent
1991	19.688
1992	21.719
1993	22.676
1994	22.609
1995	21.493
1996	20.561
1997	23.894
1998	21.28
1999	19.633
2000	16.672
2001	18.517
2002	20.257
2003	18.212
2004	16.483
2005	15.874
2006	14.325
2007	12.452
2008	10.106
2009	11.522
2010	11.778
2011	12.627
2012	11.976
2013	11.255
2014	10.552
2015	10.865
2016	10.41
2017	10.228
2018	9.956
2019	9.657
2020	9.367
2021	9.101
2022	8.851