quartic fit (13%2C 61.8)%2C (19%2C 40)%2C (22%2C 33.)%2C (25%2C 28.7)%2C (30%2C 22.9)%2C (38%2C 17.1)%2C (49%2C 12.4)%2C (60%2C 9.5)

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