condition mean min max ZT0-3 4.055361666666666 3.464645 4.63574 ZT4-7 2.524305 2.524305 2.524305 ZT8-11 2.2864250000000004 2.2864250000000004 2.2864250000000004 ZT12-15 4.078545 3.681985 4.475105 ZT16-19 2.240745 2.240745 2.240745 ZT20-23 4.778055 4.778055 4.778055