WASHINGTON (AP) – Most states now require that teachers be evaluated, at least in part, on student test scores – a move that’s drawn fierce criticism from teachers’ unions.

A comprehensive state-by-state analysis by the National Council on Teacher Quality shows 42 states and the District of Columbia require student achievement be considered in teacher evaluations. That’s up sharply from six years ago when only 15 states linked scores to evaluations.

The Washington-based think tank says the last decade has seen a “dramatic transformation” in the way teachers are evaluated.

A majority of states adopted performance-based teacher evaluations as part of the Obama administration’s Race to the Top initiative, which has awarded $4 billion in grant money to states promising reforms on teacher reviews and adopting higher academic standards such as Common Core.