Year	Percent
1991	39.712
1992	40.285
1993	40.312
1994	38.934
1995	38.017
1996	38.33
1997	37.445
1998	37.804
1999	38.023
2000	37.158
2001	37.459
2002	36.83
2003	36.538
2004	36.051
2005	36.602
2006	34.906
2007	31.252
2008	30.816
2009	29.955
2010	28.684
2011	29.653
2012	28.532
2013	28.316
2014	29.045
2015	29.267
2016	29.223
2017	30.102
2018	29.683
2019	29.192
2020	28.74
2021	28.296
2022	27.833