Actually, thats not great advice (mine above) on its own.
You'll be better off making separate data pulls. Put the keywords into groups with similar volumes, and pull each group separately.
Then plot them together. You'll get a clear view of the trends but no (or at least less) clarity on relative volumes.
(Also pull all together so you understand the ratios between the large and small volumes.)
My suggestion above is better for relative volumes, but you may find the trend data lacks precision for the lower volume terms