What is the spawn rate of the elemental drakes?

With Patch 6.9, Riot introduced four elemental drakes types: Cloud, Infernal, Mountain, and Ocean–any of which will randomly spawn during a game.

My question then is, “Do all the elemental drakes have an equal chance of spawning or do some drakes spawn more often than others?”

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  • 3 Solutions collect form web for “What is the spawn rate of the elemental drakes?”

    They spawn at a 25% chance each at first each but only 3 of the types will spawn each game.

    Patch 6.9 nodes about the elemental drakes: http://na.leagueoflegends.com/en/news/game-updates/patch/patch-69-notes

    To add on to the other posts:

    Information that is agreed upon

    • 3 elemental drake types spawn a game
    • Elemental drakes spawn every 6 minutes until 35 minutes into the game
    • Elder Dragon spawns starting the 35 minute mark, spawning every 10 minutes

    Slightly debated is the actual spawn rate of each type of drake.

    This reddit post seems to be popular, where they did an experiment to check the spawn rates. They took 100 drake spawns from 20 games and recorded them. The results were

    • Water: 33%
    • Earth: 21%
    • Fire: 22%
    • Air: 24%

    However, the method of obtaining the data is skewed. Only 3 drake types can spawn a game, which means the spawn rates become 33% for those drakes. With the random selection of dragon types, it can easily skew the overall spawn rates for drakes.

    Just because I like statistics, I did some calculations despite the small sample size. The chances of Water Drake having a 33% appearance rate with an actual rate of 25% should be about 9% (assuming the actual experiment is done correctly). The other largest discrepancy is the Earth Drake, at 21%, which still has a 40% chance of occurring due to normal deviations. So even with the skewed data, the 25% of each isn’t unreasonable. Doing a Chi Squared test yields a 0.30 P value, which suggests that the hypothesis that the 25% spawn rate is accepted.

    To accurately test the hypothesis, you would need to take the first drake spawned in each game only. However, since the initial test seems to confirm the hypothesis anyway, it’s unneeded.

    I dont know the exact spawn rates, but here is a reddit post about the actual spawn rates.

    The actual general spawn rates seem to be:

    • Water: 33%
    • Earth: 21%
    • Fire: 22%
    • Air: 24%

    Edit:
    To clarify the answer:
    The spawn rate should be 25% for each drake, according to this Riot comment

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