Year	Percent
1991	34.517
1992	32.834
1993	32.696
1994	32.02
1995	31.837
1996	30.924
1997	30.562
1998	30.005
1999	30.52
2000	26.697
2001	27.35
2002	24.487
2003	24.027
2004	21.455
2005	18.509
2006	17.129
2007	16.643
2008	16.949
2009	17.134
2010	17.381
2011	17.836
2012	17.718
2013	17.347
2014	15.982
2015	15.66
2016	15.36
2017	15.155
2018	14.783
2019	14.453
2020	14.116
2021	13.799
2022	13.492