We outlined this process a bit in the Carbon Leadership Forum’s LCA Practice Guide. See page 28.
Normalize per population and weight based on impacts importance (value judgement).
Understanding the numbers in context is important. For example, for most building materials the ozone depletion impacts are minimal so even if increased by 500% it wouldn’t matter. I use the analogy that if you have a ‘clean’ gymnasium, it might still have one grain of sand in it. If you increased the amount of sand on the gym floor by 500% you’d now have 5 grains of sand. I’d still call it clean.