tank level chart

I've lost track of a chart for calculating fuel level in a 1,000 gallon heating oil tank.

It gives corresponding fuel level based on dipstick measurements in inches.
Currently it's reading 8.5" and our supplier says that's about 75 gallons.

I'll eventually find this buried somewhere in various stacks of paper but in the meantime if someone could point me to a downloadable chart I would appreciate it very much.