Sorry for saying so, I don't think that's right.
It seems to me that 9 out of 13 times the dealer won't bust on the next card and out of those 9 times, 5 cards will give him a pat hand, not 7. Four will give him another stiff (A, 2, 3, 4 --> 13, 14, 15, and 16). And for those four stiff...