condition mean min max ZT0-3 2.1040283333333334 1.7027299999999999 2.57611 ZT4-7 1.8169149999999998 1.8169149999999998 1.8169149999999998 ZT8-11 2.5598650000000003 2.5598650000000003 2.5598650000000003 ZT12-15 3.1227850000000004 2.820355 3.425215 ZT16-19 2.6348000000000003 2.6348000000000003 2.6348000000000003 ZT20-23 3.704085 3.704085 3.704085