Items can often have a stat "on Hit" that is applied every time you hit with that skill. The "on Hits" come in two flavors a "static" value and a percentage. Because the speeds and number of enemies hit with each skill are different, Blizzard implemented a modifier to static value "on Hits". For this reason, the static values are charted out to help you decided how best to refresh your life or mana.The chart below shows the scaling percentage. 

* Bleed (%)* Blind (%)* Chill (%)* Fear (%)* Freeze (%)* Immobilize (%)* Knockback (%)* Life (static)* Mana (static)* Slow (%)* Stun (%)