Year	Percent
1991	19.131
1992	19.833
1993	21.11
1994	20.798
1995	22.425
1996	21.232
1997	21.494
1998	20.393
1999	17.676
2000	17.255
2001	22.169
2002	22.485
2003	23.921
2004	24.749
2005	26.574
2006	26.621
2007	29.403
2008	29.733
2009	29.834
2010	31.693
2011	32.727
2012	34.258
2013	35.202
2014	34.303
2015	33.593
2016	35.073
2017	34.458
2018	34.341
2019	34.281
2020	34.293
2021	34.358
2022	34.475