You should check out this thread: http://giftedissues.davidsongifted.org/BB/ubbthreads.php/topics/75032/MAP_tests.html#Post75032

You'll find links to percentiles, ranges of challenge and a lot of other good info!

As for a math score of 213 in 1st grade, that is an excellent (literally off the charts) score for 1st grade. With only that info and getting the same range more than once, I think you have an excellent case for subject acceleration.