Catch Rate

Did you really get through your entire pokedex doing the math or there's an hidden stat I didn't know about? ahah

There is no way for me to accurately know.

I hatch...therefore over 500 of mine are guaranteed to be 100%
I evolve...so those sightings are going to be 100%
Anything I see in a gym that was not in my dex, will be 0%
All this before I mention that at times I just stop trying to catch a mon for what ever reason.

86.64%

90% for pidgeys

Some Pokemon show as seen just because you interacted with them in a gym. As a result, I show Kangaskhan and Farfetch'd as 1 seen, 0 caught. Same with Muk.
Also, the stats include hatched Pokemon. I have seen and caught 15 Arbok. I think all were probably hatched.