It varies a bit over time since we have access to more ways of gaining power and events to benefit from, but to give a rough idea, I'll list out what I know to be power that is pretty promising by level.

Level 60: 20k (It's a good goal to strive for, it takes some work but it's absolutely obtainable as a free player and you'll have a good foundation to build from as you level, the very average player probably wont quite hit it unless they try.)

Level 70: 30k (Many level 70s in reality either only barely hit 20k here or not at all, people are just that bad at the game. Anything over about 25k at 70 isn't too bad but 30 would be a strong showing)

Level 80: 40k (This is a little more normal, obviously the higher the better but if you can get to about here, it could be a lot worse)

Overall you're not doing terribly but it could be better, the fact you're asking at all is promising, so just keep at it, keep learning about the different ways of getting stronger and you'll be fine.

Oh yeah, people who do that sort of thing are the worst.

I'm Kidding.

It's a funny topic for me because I'm the worst offender I've seen so far of level freezing (I've searched through a good number of servers for people close to my power-to-level ratio and found several who are close but usually not quite) and I never even started doing it with PVP in mind, I did it because I just wanted to see what would happen if one didn't level unless they had to and to make it easier on myself as a free player to save materials & resources.