condition mean min max ZT0-3 6.883831666666667 6.762895 6.954420000000001 ZT4-7 4.302515 4.302515 4.302515 ZT8-11 4.34346 4.34346 4.34346 ZT12-15 5.6302325 4.534195 6.7262699999999995 ZT16-19 5.16434 5.16434 5.16434 ZT20-23 7.008835 7.008835 7.008835