condition mean min max ZT0-3 7.219635 7.219635 7.219635 ZT4-7 5.2418499999999995 5.2418499999999995 5.2418499999999995 ZT8-11 4.887105 4.887105 4.887105 ZT12-15 5.244325 5.244325 5.244325 ZT16-19 6.542125 6.542125 6.542125 ZT20-23 6.424885 6.424885 6.424885