Year	Percent
1991	27.827
1992	27.332
1993	26.807
1994	25.966
1995	24.441
1996	23.104
1997	21.436
1998	21.572
1999	21.681
2000	21.235
2001	21.171
2002	21.06
2003	20.923
2004	20.309
2005	20.054
2006	19.841
2007	19.653
2008	19.491
2009	19.36
2010	19.883
2011	20.87
2012	23.954
2013	21.804
2014	22.403
2015	21.975
2016	21.095
2017	21.112
2018	21.092
2019	21.082
2020	21.069
2021	21.042
2022	21.002