condition mean min max ZT0-3 20.77965 20.77965 20.77965 ZT4-7 19.8697 19.8697 19.8697 ZT8-11 17.97905 17.97905 17.97905 ZT12-15 19.28685 19.28685 19.28685 ZT16-19 18.57725 18.57725 18.57725 ZT20-23 21.65445 21.65445 21.65445