Dynamically number multi-page survey

Hi

I'm trying to create a multiple-page questionnaire with routing, so want to dynamicallly number the questions so it goes up in steps of 1 for the user no matter which route they use. I've got as far as <cfset session.qnumber=#session.qnumber#+1> but that does not work if you use the 'back' button.

Is there a good way to do this, please?

many thanks

Dave