Year	Percent
1991	40.42
1992	30.756
1993	32.316
1994	31.118
1995	37.231
1996	42.019
1997	42.342
1998	38.75
1999	37.573
2000	35.885
2001	37.842
2002	35.606
2003	35.854
2004	35.251
2005	33.697
2006	33.992
2007	33.691
2008	32.208
2009	32.313
2010	31.819
2011	31.836
2012	31.527
2013	31.226
2014	27.064
2015	28.259
2016	27.699
2017	27.741
2018	27.63
2019	27.634
2020	27.737
2021	27.964
2022	28.03