Gruff Charting Question

I am using Gruff to chart 2 sets of data and have run into a problem,
the numbers between the two sets are so far apart that the first set
appears as a mostly straight line at the top and the second a mostly
straight line at the bottom.

Is there a way to set the min/max vertical column values so that I can
squeeze the data closer together so that there is more ‘movement’? If
there is not does anyone know a way to mathematically adjust the data? I
tried Log10 and log already and the same effect was visible even though
the numers were much smaller in relation to their original values.

Any help appreciated!