Year	Percent
1991	31.599
1992	30.425
1993	30.036
1994	29.238
1995	28.095
1996	28.568
1997	25.873
1998	23.573
1999	21.878
2000	20.475
2001	16.706
2002	19.615
2003	22.584
2004	18.737
2005	17.811
2006	14.573
2007	12.736
2008	14.233
2009	16.695
2010	19.398
2011	16.472
2012	14.519
2013	12.394
2014	10.322
2015	9.994
2016	9.516
2017	9.325
2018	9.022
2019	8.73
2020	8.451
2021	8.203
2022	8