tracking growth

I did the math today and my dumeril boa has grown 11 inches in 7 months, averages out to 1.5 inches a month. Have no info on bp's got them recently, I was wondering if any of you track growth like this or have any comparisons.

All I can add is my albino cali king averaged 1" a month growth.

I don't keep a very good (regularly updated) record of growth by length, but I have a weekly (sometimes more often) record of growth by weight. My normal has put on a little under 300g in a little over 2 months. He's still a baby, and still only gets 2 Adult mice a week.