condition mean min max ZT0-3 12.153223333333333 5.89997 15.5043 ZT4-7 5.85586 5.85586 5.85586 ZT8-11 6.4713 6.4713 6.4713 ZT12-15 8.062785 7.019575 9.105995 ZT16-19 11.631599999999999 11.631599999999999 11.631599999999999 ZT20-23 17.1573 17.1573 17.1573