Part of me thinks that it may be a typo of "budged" which means to shove or move given the context. But as far as I know, budget only has one meaning: an allocation or determined amount. Hope this helped :)

Definitely a mistake. "Budgeted" should be "budged", so it means numbers that have changed only a little.

It doesn't make sense the way it's written. It might have been a typo, with the author meaning to say 'numbers that have barely budged over the past decade.' It's also possible that they used the word 'budget' in a strange way and the author meant something like 'numbers that have barely been within budget'.

May be that's mean regulate/set