condition mean min max ZT0-3 9.704861 9.704861 9.704861 ZT4-7 8.6150125 8.6150125 8.6150125 ZT8-11 8.156631 8.156631 8.156631 ZT12-15 8.0520545 8.0520545 8.0520545 ZT16-19 9.231545 9.231545 9.231545 ZT20-23 8.4098425 8.4098425 8.4098425