condition mean min max ZT0-3 4.977185 4.977185 4.977185 ZT4-7 3.24865 3.24865 3.24865 ZT8-11 3.952565 3.952565 3.952565 ZT12-15 6.766305 6.766305 6.766305 ZT16-19 6.4914000000000005 6.4914000000000005 6.4914000000000005 ZT20-23 4.92234 4.92234 4.92234