Anyone have any idea of the ratio used to make an out of court offer?

claim: Future loss of earnings �220,000. plus pain and suffering, etc. Total claim somewhere between �250,000 and �330,000. I am not accepting any partial blame. Is there a % used as a guideline for out of court settlement offers? Court papers lodged this week. Independent barrister (�600 per hour!) gave me an incredibly good % chance of sucess.