Year	Percent
1991	34.258
1992	28.364
1993	30.17
1994	32.464
1995	31.895
1996	30.128
1997	34.629
1998	33.775
1999	34.921
2000	35.194
2001	35.244
2002	35.331
2003	34.673
2004	34.66
2005	33.552
2006	32.982
2007	32.813
2008	30.582
2009	29.538
2010	29.298
2011	29.051
2012	28.85
2013	28.6
2014	28.491
2015	28.117
2016	27.916
2017	27.394
2018	27.394
2019	27.365
2020	27.347
2021	27.328
2022	27.309