I don't have enough information. There are various ways of measuring height, and every ship captain
knows what his is - it's even on a plaque near the bridge, if my memory is right.
If you want an average, or some examples coming in and out of Houston, get in touch with the Houston ship pilots. They bring them in and out, and might be able to help you.
I do have a brother-in-law who is a ship pilot at Corpus Christi Aransus Pass. I'll ask him or put you in touch if it would help.