condition mean min max ZT0-3 7.514383 7.514383 7.514383 ZT4-7 8.2994305 8.2994305 8.2994305 ZT8-11 7.2104040000000005 7.2104040000000005 7.2104040000000005 ZT12-15 7.8534545 7.8534545 7.8534545 ZT16-19 8.307565499999999 8.307565499999999 8.307565499999999 ZT20-23 8.258637 8.258637 8.258637