Additionally, Brooks muses that "good" programmers are generally five to ten times as productive as mediocre ones.
https://en.wikipedia.org/wiki/The_Mythical_Man-Month
“In one of their studies, Sackman, Erikson, and Grant were measuring performances of a group of experienced programmers. Within just this group, the ratios between best and worst performances averaged about 10:1 on productivity measurements and an amazing 5:1 on program speed and space measurements!” – The Mythical Man-Month