condition mean min max ZT0-3 15.062134 15.062134 15.062134 ZT4-7 17.5272025 17.5272025 17.5272025 ZT8-11 15.2223765 15.2223765 15.2223765 ZT12-15 14.921572999999999 14.921572999999999 14.921572999999999 ZT16-19 15.689672999999999 15.689672999999999 15.689672999999999 ZT20-23 15.0934185 15.0934185 15.0934185