Consulting the Codex…
RS3 · Skills · Activities · Quests
The Codex keeps its readings for 400 days, so you can go back that far, to the first day it read Bigski.
Defence 80 → 90, 3.4m XP
Herblore 99 → 106, 12.3m XP
Summoning 82 → 96, 7.1m XPWeakest area: Summoning. Summoning 82 → 96, 7.1m XP. Quests need a public profile, so the quest checks are left out of the score.