Year	Percent
1991	24.033
1992	23.848
1993	18.6
1994	19.341
1995	21.882
1996	22.29
1997	22.193
1998	23.872
1999	26.636
2000	28.196
2001	27.082
2002	28.153
2003	25.23
2004	26.005
2005	29.365
2006	30.332
2007	29.273
2008	27.117
2009	27.524
2010	24.682
2011	21.042
2012	21.967
2013	22.13
2014	22.589
2015	19.507
2016	18.911
2017	18.801
2018	18.836
2019	18.819
2020	18.81
2021	18.819
2022	18.828