Year	Percent
1991	31.235
1992	31.477
1993	30.368
1994	31.63
1995	30.785
1996	30.13
1997	29.996
1998	28.605
1999	30.079
2000	30.737
2001	30.916
2002	31.221
2003	30.893
2004	31.098
2005	31.054
2006	32.109
2007	31.52
2008	32.531
2009	32.707
2010	32.143
2011	31.897
2012	31.367
2013	30.991
2014	30.757
2015	30.334
2016	30.307
2017	30.758
2018	30.596
2019	30.354
2020	30.025
2021	29.627
2022	29.165