condition mean min max ZT0-3 268.603367 268.603367 268.603367 ZT4-7 288.0736105 288.0736105 288.0736105 ZT8-11 336.412349 336.412349 336.412349 ZT12-15 321.84797749999996 321.84797749999996 321.84797749999996 ZT16-19 421.9067885 421.9067885 421.9067885 ZT20-23 377.886553 377.886553 377.886553