You figured wrong. Who cares what Biden's was, it's irrelevant. I don't know what Bidens was, but according to Gallup:

Trump's job approval rating is 15 points below the historical average for all other elected presidents in mid-February since 1953, but it is five points higher than the February reading in his first term. Bill Clinton has the next lowest mid-February rating for a newly inaugurated president -- which, at 51%, is six points higher than where Trump is now. John Kennedy (72%) and Jimmy Carter (71%) were the highest rated at this point in their presidencies.

To my knowledge, no other President, ever, in history, self reported his own rating 25 percent higher than all the other polls.