condition mean min max ZT0-3 7.363795 7.363795 7.363795 ZT4-7 5.29314 5.29314 5.29314 ZT8-11 7.19008 7.19008 7.19008 ZT12-15 9.456315 9.456315 9.456315 ZT16-19 9.504584999999999 9.504584999999999 9.504584999999999 ZT20-23 8.249925 8.249925 8.249925