condition mean min max ZT0-3 2.0988083333333334 1.742675 2.57446 ZT4-7 1.384425 1.384425 1.384425 ZT8-11 2.271645 2.271645 2.271645 ZT12-15 3.9235025 3.53672 4.310285 ZT16-19 3.5051449999999997 3.5051449999999997 3.5051449999999997 ZT20-23 4.355874999999999 4.355874999999999 4.355874999999999