Year	Percent
1991	33.419
1992	33.442
1993	33.205
1994	33.278
1995	33.008
1996	33.108
1997	29.945
1998	30.042
1999	30.248
2000	30.4
2001	30.271
2002	30.233
2003	28.113
2004	28.156
2005	28.048
2006	27.804
2007	27.986
2008	27.998
2009	27.865
2010	27.711
2011	27.653
2012	27.751
2013	27.739
2014	27.735
2015	27.82
2016	27.888
2017	27.879
2018	27.87
2019	27.859
2020	27.849
2021	27.837
2022	27.826