What is a "Market Related" salary for a Marketing Assistant

I have been a marketing and management assistant for a year; then I was a media planner and buyer for another year, I have now been a marketing assistant - reporting directly to the CEO in a SME (60 staff) for just over 2 years.

I have been involved with projects as varied as recommending we look at changing our brand - helping to decide on the branding agency - deciding on an organisation to rework our website using cutting edge SEO techniques as well as the more traditional functions of direct marketing, ATL and BTL marketing and advertising. Internal communications etc.

I feel that the title of "Marketing assistant" does not fully encapsulate my role as I handle many tasks which would ordinarily fall into communications management and brand management.

Can anyone tell me what a "market related" salary would be for someone in my position..!?!