Loot Boxes can have items with rarities from Common, Rare, Epic, and Legendary.
What I'd like to know is, with the nature of Loot Boxes, what are the drop rates of Common/Rare/Epic/Legendary items? I'd especially like to know what are the chances to get a Legendary skin from a Loot Box.
For example, in TF2, Valve has made all crates a 1% flat chance to get an Unusual Hat. In CS:GO, it's the same thing, with a 1% to get an Exceedingly Rare Special Item. In Overwatch, what are my chances of getting a specific rarity from a Loot Box?