condition mean min max ZT0-3 8.615955 7.70767 9.524239999999999 ZT4-7 11.8375 11.8375 11.8375 ZT8-11 15.73315 15.73315 15.73315 ZT12-15 0 0 0 ZT16-19 15.4592 15.4592 15.4592 ZT20-23 12.86855 12.86855 12.86855