Design my CSS progress bar (sbcredits)

I need a thermometer themed bar to indicate the number of 'credits' someone has in their account. Attached is the graphic I'm using. I'd like this done in CSS please. This will be coded so that the 'cover' layer width will be worked out as a % of the number of credits they have left (e.g.) if they buy 10 credits and have used 5 then it'll calculate that to 50%. Somewhere in the HTML, I need to be able to set that 50% value as it could be anything from 0% to 100%. Please read my attached notes for full details. Please bid or ask any questions if you are interested.