condition mean min max ZT0-3 7.897365 7.897365 7.897365 ZT4-7 5.4355 5.4355 5.4355 ZT8-11 6.9345 6.9345 6.9345 ZT12-15 8.48785 8.48785 8.48785 ZT16-19 10.757105 10.757105 10.757105 ZT20-23 7.851935 7.851935 7.851935