[["", "2015", "2014", "2013"], ["balance at beginning of year", "$ 38.9", "$ 38.3", "$ 45.3"], ["additions charged to expense", "22.7", "22.6", "16.1"], ["accounts written-off", "-14.9 ( 14.9 )", "-22.0 ( 22.0 )", "-23.1 ( 23.1 )"], ["balance at end of year", "$ 46.7", "$ 38.9", "$ 38.3"]]