Digital BW, The Print

Am trying to create curves and determine densities using this gray 
scale and coordinating with my Epson flatbed scanner...have looked 
everywhere and cannot find accurate density numbers/info on this, and I 
don't have a densitometer, and my scanner is unreliable as a starting 
point. (This is the rectangle 20-step Kodak Gray Scale with 
the "A", "M", and "B" along with the numbers.) 

Any help greatly appreciated...Mark