How many cc is the average forehead filler?

It's the same as my forehead. How many cc should I put in if it's like this?
 They say that fat grafting isn't good if it doesn't engraft, so I thought it would be too burdensome, so I thought I'd try fillers first. They said
 it's a bit expensive compared to hospitals around here, but looking at the before and after photos, it sure looks like they're doing it naturally, right??
 They say it's a hospital famous for fillers, and even though they're expensive, they're good at it, so it's probably a good idea to go there and get it done, right?
 What about people who have had it? Do you recommend fillers?