Why are you expected to produce metrics about your career in your CV these days? What if your contribution to your company (or society) isn't measurable by a percentage? Works fine for "reduced payroll overheads by 20%" but what am I supposed to say - "Increased machine generated metadata for radio content by 100%?"
Doctors don't have to do it. "Provided antibiotics to 100% of patients who needed antibiotics"
"Diagnosed 20% more chronic disease than in the last year"
"Referred 10% of all patients to hospital specialsists"