condition mean min max ZT0-3 4.24 4.153855 4.326145 ZT4-7 5.223155 5.223155 5.223155 ZT8-11 9.589405 9.589405 9.589405 ZT12-15 0 0 0 ZT16-19 12.21421 12.21421 12.21421 ZT20-23 6.28796 6.28796 6.28796