condition mean min max ZT0-3 2.7882016666666667 1.5342 3.45363 ZT4-7 0.597391 0.597391 0.597391 ZT8-11 0.5696545 0.5696545 0.5696545 ZT12-15 1.16011425 1.0938295 1.226399 ZT16-19 2.039685 2.039685 2.039685 ZT20-23 3.205355 3.205355 3.205355