condition mean min max ZT0-3 1.914965 1.914965 1.914965 ZT4-7 3.76816 3.76816 3.76816 ZT8-11 3.6524 3.6524 3.6524 ZT12-15 2.63786 2.63786 2.63786 ZT16-19 2.75298 2.75298 2.75298 ZT20-23 1.607335 1.607335 1.607335