These are two example Numbers spreadsheet that allow you to hand-tweak the axis-mapping and translation of interpolation values.
The Weight spreadsheet is a simple example of an exponential distribution.
The Optical Size spreadsheet is an example of how to deal with non-continuous ranges in Numbers.
In both examples the black curve in the background of the graphs are Number’s attempt at auto-fit on the data you enter into the table. You can change the curve type to exponential, logarithmic or other types.