condition mean min max ZT0-3 7.375632 7.375632 7.375632 ZT4-7 7.5428045 7.5428045 7.5428045 ZT8-11 7.441121 7.441121 7.441121 ZT12-15 7.160832 7.160832 7.160832 ZT16-19 6.8826315000000005 6.8826315000000005 6.8826315000000005 ZT20-23 7.0940085 7.0940085 7.0940085