condition mean min max ZT0-3 8.473593333333334 8.473593333333334 8.473593333333334 ZT4-7 6.50373 6.50373 6.50373 ZT8-11 6.10643 6.10643 6.10643 ZT12-15 6.335224999999999 6.335224999999999 6.335224999999999 ZT16-19 9.54368 9.54368 9.54368 ZT20-23 8.16023 8.16023 8.16023