condition mean min max ZT0-3 7.986423 7.986423 7.986423 ZT4-7 8.603179 8.603179 8.603179 ZT8-11 8.302347000000001 8.302347000000001 8.302347000000001 ZT12-15 9.242450999999999 9.242450999999999 9.242450999999999 ZT16-19 9.519515 9.519515 9.519515 ZT20-23 8.803582500000001 8.803582500000001 8.803582500000001