How old was Manon?

***minor spoilers***

I've not read the book so for anyone who has, is there a mention of how old Manon is when MDS is set?

I was guessing 16 or 17? Towards the end of the film Ugolin & Cesar are accused of blocking the stream '8 or 9 years ago', so we know its that long since the start of JDF but I don't think we know the age of Manon at the start of the film (unless I'd missed something). I thought about 8 so would put her at 16/17? Then again I'm pretty useless at guessing kids ages so could be a couple of years out!!