My 3 are a similar age to yours and I find they tend to have mad, energetic bursts which can last for up to 30 minutes.
Then they tend to wander around eating and ruble strutting (this is our boars favorite past time - go Eddi) and generally interacting with each other for a while.
Then they sleep for around 30 mins - 1 hour, and repeat the whole thing over!
So overall I would say they are usually fairly active for over 50% of the day.