Year	Percent
1991	36.998
1992	37.613
1993	37.976
1994	37.981
1995	37.237
1996	36.521
1997	36.583
1998	36.466
1999	36.854
2000	37.571
2001	36.898
2002	36.239
2003	35.952
2004	34.84
2005	33.647
2006	31.574
2007	31.011
2008	31.764
2009	31.799
2010	31.391
2011	31.121
2012	30.763
2013	30.121
2014	29.903
2015	29.796
2016	30.072
2017	29.965
2018	29.295
2019	28.569
2020	27.894
2021	27.125
2022	26.467