Nothing exceptional there, there was always at least one other child in my classroom which had skipped one grade (so, about 8%?).
My 4th grade teacher was the one who arranged me skipping 5th -- she couldn't take me being an all A student without putting in one ounce of work at school. That was more unusual, true.
So I'd say solidly MG, right? I wish I could get my hands on those test results from 4th grade, just to know. Though I had to laugh when reading some of the testing threads -- I still remember driving the evaluator wild on what was probably the first Similarities question: plum and apricot. I spent 5 increasingly desperate minutes going though answers like "they are both from the genus prunus? both have flowers with five petals and sepals?..." while thinking "oh my, this is really hard, I am going to flunk the test"... and she finally broke down and told me the answer was fruits (probably thinking "FRUITS! What's wrong with you???"

). And then sitting back in my chair thinking "well, that was dumb!" rather scornfully.