Year	Percent
1991	32.612
1992	35.277
1993	36.297
1994	34.703
1995	35.29
1996	34.237
1997	37.283
1998	38.679
1999	40.861
2000	42.786
2001	41.772
2002	35.697
2003	36.083
2004	32.21
2005	31.661
2006	29.919
2007	28.31
2008	27.327
2009	27.777
2010	29.948
2011	27.773
2012	28.671
2013	28.373
2014	27.585
2015	25.568
2016	23.463
2017	23.406
2018	22.904
2019	22.591
2020	22.173
2021	21.927
2022	21.634