Year	Percent
1991	30.625
1992	31.09
1993	30.933
1994	31.1
1995	31.799
1996	32.02
1997	31.889
1998	32.041
1999	31.635
2000	31.832
2001	31.736
2002	31.322
2003	31.25
2004	31.651
2005	30.696
2006	30.346
2007	30.153
2008	29.589
2009	29.373
2010	29.911
2011	29.747
2012	29.601
2013	29.559
2014	29.185
2015	28.741
2016	28.168
2017	27.906
2018	27.783
2019	27.684
2020	27.609
2021	27.535
2022	27.461