condition mean min max ZT0-3 2.146485 1.91626 2.47668 ZT4-7 1.5909300000000002 1.5909300000000002 1.5909300000000002 ZT8-11 2.673 2.673 2.673 ZT12-15 4.4725225 4.31816 4.626885 ZT16-19 4.928744999999999 4.928744999999999 4.928744999999999 ZT20-23 3.417655 3.417655 3.417655