condition mean min max ZT0-3 21.469833333333334 11.1006 30.2237 ZT4-7 7.11107 7.11107 7.11107 ZT8-11 9.466405000000002 9.466405000000002 9.466405000000002 ZT12-15 20.29175 17.86425 22.719250000000002 ZT16-19 24.543100000000003 24.543100000000003 24.543100000000003 ZT20-23 39.6004 39.6004 39.6004