In fact, I don't think Bilbo was more resistant. The numbers you created were arbitrary because the Ring had a greater effect based upon the volatility of the environment it was in. The ring was just a trinket until the Nine were released to look for it, and even that took a few years before it really started being a problem for Frodo.
I don't think constitution is a measurable stat outside of the purposes of a trading card game. But in general, Elves had the highest constitution, followed by Hobbits, then Dwarves, then Men.
Congrats on your 2450th post, Lurtzy. I got mine earlier today.
-wtk