NEW YORK (AP) — U.S. kindergarten vaccination rates inched down again last year and the share of children with exemptions rose to an all-time high, according to federal data posted Thursday.

The fraction of kids exempted from vaccine requirements rose to 3.6%, up from 3.3% the year before. It’s the third record-breaking year in a row for the national average exemption rate, and the vast majority are parents withholding shots for nonmedical reasons. The CDC also reported the median exemption rate among 48 states and the District of Columbia was 4.1%.

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