condition mean min max ZT0-3 4.538436666666667 3.903555 5.365705 ZT4-7 7.143000000000001 7.143000000000001 7.143000000000001 ZT8-11 7.395425 7.395425 7.395425 ZT12-15 15.347025 15.1848 15.509250000000002 ZT16-19 15.0374 15.0374 15.0374 ZT20-23 11.89925 11.89925 11.89925