Year	Percent
1991	36.507
1992	35.549
1993	34.733
1994	33.648
1995	33.183
1996	32.295
1997	31.449
1998	30.1
1999	29.28
2000	28.465
2001	28.637
2002	27.917
2003	27.535
2004	27.508
2005	27.299
2006	27.008
2007	26.944
2008	26.874
2009	25.979
2010	25.969
2011	26.119
2012	25.85
2013	25.7
2014	25.48
2015	25.344
2016	25.195
2017	24.764
2018	24.411
2019	23.998
2020	23.569
2021	23.208
2022	22.873