Year	Percent
1991	43.276
1992	43.427
1993	42.664
1994	41.793
1995	41.879
1996	39.599
1997	39.008
1998	40.459
1999	39.643
2000	39.439
2001	39.234
2002	41.583
2003	41.817
2004	41.706
2005	37.813
2006	36.305
2007	38.593
2008	37.687
2009	36.856
2010	36.28
2011	36.781
2012	35.989
2013	36.544
2014	36.651
2015	34.635
2016	29.971
2017	29.897
2018	29.842
2019	29.787
2020	29.732
2021	29.676
2022	29.62