Year	Percent
1991	37.255
1992	38.861
1993	45.564
1994	39.472
1995	39.711
1996	39.505
1997	38.356
1998	36.305
1999	37.024
2000	36.276
2001	37.535
2002	38.159
2003	36.674
2004	36.857
2005	38.075
2006	36.414
2007	36.182
2008	38.069
2009	34.394
2010	33.007
2011	31.697
2012	36.691
2013	35.273
2014	35.786
2015	34.911
2016	34.461
2017	33.384
2018	32.453
2019	31.547
2020	30.703
2021	29.947
2022	29.201