condition mean min max ZT0-3 7.174585 7.174585 7.174585 ZT4-7 7.09507 7.09507 7.09507 ZT8-11 4.73656 4.73656 4.73656 ZT12-15 5.2340599999999995 5.2340599999999995 5.2340599999999995 ZT16-19 6.88419 6.88419 6.88419 ZT20-23 7.278675 7.278675 7.278675