condition mean min max ZT0-3 6.721045 6.721045 6.721045 ZT4-7 5.65041 5.65041 5.65041 ZT8-11 6.737665 6.737665 6.737665 ZT12-15 8.49069 8.49069 8.49069 ZT16-19 10.16666 10.16666 10.16666 ZT20-23 6.720745 6.720745 6.720745