Year	Percent
1991	33.7
1992	32.373
1993	26.636
1994	25.087
1995	17.533
1996	20.105
1997	21.616
1998	25.086
1999	24.235
2000	23.344
2001	22.644
2002	21.089
2003	22.497
2004	25.817
2005	25.599
2006	26.997
2007	26.752
2008	27.208
2009	25.889
2010	23.626
2011	24.942
2012	24.166
2013	23.854
2014	23.23
2015	22.926
2016	22.105
2017	21.694
2018	21.714
2019	21.613
2020	20.956
2021	20.412
2022	19.97