Complex sentence: Different measurement tools (see below) read different ozone depletion averages ranging from 5-90%, however some of the tools (specifically the one's that reported lower averages) did not take accurate readings or missed a couple of years.
Split into simpler sentences: Different measurement tools (see below) read different ozone depletion averages ranging from 5-90%. However, some of the tools (specifically the ones that reported lower averages) did not take accurate readings or missed a couple of years.