condition mean min max ZT0-3 1.615284 1.615284 1.615284 ZT4-7 3.123445333333333 3.123445333333333 3.123445333333333 ZT8-11 2.1549869999999998 2.1549869999999998 2.1549869999999998 ZT12-15 1.591062 1.591062 1.591062 ZT16-19 6.984333 6.984333 6.984333 ZT20-23 2.442441 2.442441 2.442441