condition mean min max ZT0-3 8.016131 8.016131 8.016131 ZT4-7 8.2944055 8.2944055 8.2944055 ZT8-11 8.9423985 8.9423985 8.9423985 ZT12-15 9.0030565 9.0030565 9.0030565 ZT16-19 8.462762 8.462762 8.462762 ZT20-23 8.4818935 8.4818935 8.4818935