Year	Percent
1991	22.411
1992	21.671
1993	21.164
1994	19.996
1995	19.53
1996	19.075
1997	21.582
1998	26.094
1999	23.612
2000	22.037
2001	17.01
2002	20.892
2003	27.618
2004	30.161
2005	32.503
2006	34.643
2007	31.836
2008	29.638
2009	29.04
2010	30.55
2011	31.858
2012	31.89
2013	30.815
2014	30.486
2015	31.06
2016	30.244
2017	30.431
2018	30.001
2019	29.446
2020	28.928
2021	28.4
2022	27.863