I haven't heard the word "retarded" used in earnest to refer to intellectual disability (the replacement term) for at least a decade, and probably closer to 15 years. Note that this is a textbook case of the euphemism treadmill, where whatever term is used to intellectual disability eventually starts getting used as an insult and thus the term is changed. Eventually the old retired terms become fairly acceptable as insults, like "idiot" and "moron."