condition mean min max ZT0-3 6.165601666666666 4.63347 7.7116050000000005 ZT4-7 3.423425 3.423425 3.423425 ZT8-11 4.00335 4.00335 4.00335 ZT12-15 9.6498725 7.68394 11.615805 ZT16-19 7.3268249999999995 7.3268249999999995 7.3268249999999995 ZT20-23 9.472725 9.472725 9.472725