Year	Percent
1991	33.295
1992	31.818
1993	29.747
1994	28.508
1995	28.425
1996	28.576
1997	27.379
1998	27.218
1999	27.078
2000	27.659
2001	21.683
2002	21.992
2003	20.828
2004	20.341
2005	20.857
2006	19.259
2007	17.815
2008	17.142
2009	19.567
2010	20.899
2011	15.222
2012	14.584
2013	14.073
2014	15.654
2015	17.348
2016	16.923
2017	16.713
2018	16.221
2019	15.732
2020	15.29
2021	14.896
2022	14.515