Unlock level four
ACH_UNLOCK_LEVEL_FOUR23.5%

Achievements and their recorded unlock rates.
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ACH_UNLOCK_LEVEL_FOURACH_PLAY_LEVEL_THREEACH_UNLOCK_LEVEL_ELEVENACH_UNLOCK_LEVEL_TENACH_UNLOCK_LEVEL_NINEACH_UNLOCK_LEVEL_SIXTEENACH_UNLOCK_LEVEL_FIFTEENACH_UNLOCK_LEVEL_FOURTEENACH_UNLOCK_LEVEL_THIRTEENACH_UNLOCK_LEVEL_TWELVEACH_UNLOCK_LEVEL_EIGHTACH_UNLOCK_LEVEL_SEVENACH_UNLOCK_LEVEL_SIXACH_UNLOCK_LEVEL_FIVE