condition mean min max ZT0-3 10.973064 10.973064 10.973064 ZT4-7 13.6670275 13.6670275 13.6670275 ZT8-11 14.887592999999999 14.887592999999999 14.887592999999999 ZT12-15 15.626873 15.626873 15.626873 ZT16-19 16.7706755 16.7706755 16.7706755 ZT20-23 17.808573 17.808573 17.808573