The odds of getting an item of a specific crate is quite unfair in my opinion, for example, the legendary loot crate has a 29% chance of getting a mythic item and a 21% chance of getting a rare item, to the 22% chance of getting a legendary item. Put it simply, there's less of a chance of you getting a legendary item, than any other item, a fair odd for each crate would be 40% to get each item type corresponding to its crate.
(For personal experience, I got the levitation effect 2 times in a row, once from a Mythic crate, and the other from a Legendary one)