condition mean min max ZT0-3 15.373313 15.373313 15.373313 ZT4-7 17.5865735 17.5865735 17.5865735 ZT8-11 16.589026500000003 16.589026500000003 16.589026500000003 ZT12-15 14.895329 14.895329 14.895329 ZT16-19 14.18413 14.18413 14.18413 ZT20-23 14.1154405 14.1154405 14.1154405