condition mean min max ZT0-3 4.258526666666667 1.9191599999999998 5.531585 ZT4-7 3.02588 3.02588 3.02588 ZT8-11 3.24234 3.24234 3.24234 ZT12-15 4.29689 3.6471 4.946680000000001 ZT16-19 5.80656 5.80656 5.80656 ZT20-23 7.235025 7.235025 7.235025