condition mean min max ZT0-3 2.761725 2.058515 3.359875 ZT4-7 2.52312 2.52312 2.52312 ZT8-11 3.016235 3.016235 3.016235 ZT12-15 4.2703875 3.95116 4.589615 ZT16-19 3.114745 3.114745 3.114745 ZT20-23 3.992705 3.992705 3.992705