condition mean min max ZT0-3 2.7706566666666665 1.46234 3.462955 ZT4-7 2.2282650000000004 2.2282650000000004 2.2282650000000004 ZT8-11 2.25118 2.25118 2.25118 ZT12-15 2.2699925000000003 1.700725 2.8392600000000003 ZT16-19 3.033045 3.033045 3.033045 ZT20-23 3.886985 3.886985 3.886985