condition mean min max ZT0-3 8.422686 8.422686 8.422686 ZT4-7 10.370197000000001 10.370197000000001 10.370197000000001 ZT8-11 9.138912 9.138912 9.138912 ZT12-15 8.4669575 8.4669575 8.4669575 ZT16-19 8.569841499999999 8.569841499999999 8.569841499999999 ZT20-23 9.5537325 9.5537325 9.5537325