condition mean min max ZT0-3 8.335619 8.335619 8.335619 ZT4-7 9.0094125 9.0094125 9.0094125 ZT8-11 8.048726499999999 8.048726499999999 8.048726499999999 ZT12-15 7.8611945 7.8611945 7.8611945 ZT16-19 8.003915 8.003915 8.003915 ZT20-23 9.022621999999998 9.022621999999998 9.022621999999998