BOSTON (AP) — Advocates for changing Massachusetts’ personal income tax may have new fuel for their campaign, as a new national study suggests a more progressive income tax that requires wealthier individuals to pay higher tax rates could help states deal with revenue problems.

Standard & Poor’s, in a study released Monday, found that the improving fortunes of the nation’s top earners corresponds with a decades-long slowdown in tax revenue growth among states. The rating agency says states adopting more progressive, or graduated, income tax rates could be more insulated from the problem, though it stops short of endorsing outright such policy changes.