A new Gallup poll ranks the five living U.S. presidents by favorability, revealing who Americans view most positively—and who ranks at the bottom.

The Gallup poll — which sampled 1,001 U.S. adults between Jan. 21 and Jan. 27 — found opinions toward the men have fluctuated significantly over time.

A Gallup survey of adults living in the U.S. found that former President Barack Obama is the most favorably viewed living president, while former President Joe Biden is viewed least favorably.