condition mean min max ZT0-3 2.8693075 2.47447 3.264145 ZT4-7 3.83352 3.83352 3.83352 ZT8-11 3.82604 3.82604 3.82604 ZT12-15 0 0 0 ZT16-19 4.1332249999999995 4.1332249999999995 4.1332249999999995 ZT20-23 4.722385 4.722385 4.722385