condition mean min max ZT0-3 8.441723333333334 4.26066 10.564555 ZT4-7 3.2408599999999996 3.2408599999999996 3.2408599999999996 ZT8-11 8.203065 8.203065 8.203065 ZT12-15 11.4981125 10.351875 12.64435 ZT16-19 12.6457 12.6457 12.6457 ZT20-23 13.8348 13.8348 13.8348