condition mean min max ZT0-3 9.702619 9.702619 9.702619 ZT4-7 9.076667 9.076667 9.076667 ZT8-11 10.2311485 10.2311485 10.2311485 ZT12-15 10.635092499999999 10.635092499999999 10.635092499999999 ZT16-19 13.542665000000001 13.542665000000001 13.542665000000001 ZT20-23 12.488294499999999 12.488294499999999 12.488294499999999