condition mean min max ZT0-3 8.358445 8.358445 8.358445 ZT4-7 4.48224 4.48224 4.48224 ZT8-11 6.39468 6.39468 6.39468 ZT12-15 6.53281 6.53281 6.53281 ZT16-19 9.891425 9.891425 9.891425 ZT20-23 6.42117 6.42117 6.42117