condition mean min max ZT0-3 18.746314 18.746314 18.746314 ZT4-7 24.371161 24.371161 24.371161 ZT8-11 20.2626815 20.2626815 20.2626815 ZT12-15 14.831239499999999 14.831239499999999 14.831239499999999 ZT16-19 15.183801 15.183801 15.183801 ZT20-23 14.816668 14.816668 14.816668