pre-set ratio for co-op missions

Is there a pre-defined ratio for how the game intensifies per add-on player in co-op missions? I had completed several as a tag team but now I'm being asked to help someone else so we'll be hitting these missions as a team of 3. For example, two players equaled 97 enemies - would three players face 115 or 140. I'm curious because if you leave too many stragglers you end up getting popped on the was to extraction. SNAP, mission failed.

"El riesgo vive siempre!"