Year	%
1990	15.3409090909091
1991	15.0259067357513
1992	15.3846153846154
1993	15.4545454545455
1994	15.2173913043478
1995	15.546218487395
1996	15.6378600823045
1997	15.4471544715447
1998	15.6626506024096
1999	15.5378486055777
2000	15.6862745098039
2001	15.9090909090909
2002	16.0142348754448
2003	16.1184210526316
2004	16.4670658682635
2005	16.5311653116531
2006	16.5853658536585
2007	16.6666666666667
2008	16.798418972332
2009	16.9642857142857
2010	17.0506912442396
2011	17.0698924731183
2012	17.0441001191895
2013	16.9164882226981
2014	16.6504381694255
2015	16.2983425414365
2016	16.140350877193
2017	15.9966499162479
2018	15.9036144578313
2019	15.916149068323
2020	15.8527422990233
2021	15.8940397350993
2022	15.9712230215827