condition mean min max ZT0-3 9.197685 8.877565 9.517805 ZT4-7 10.86805 10.86805 10.86805 ZT8-11 7.945045 7.945045 7.945045 ZT12-15 0 0 0 ZT16-19 9.697705 9.697705 9.697705 ZT20-23 12.742 12.742 12.742