condition mean min max ZT0-3 8.037063 8.037063 8.037063 ZT4-7 8.485158 8.485158 8.485158 ZT8-11 8.6120385 8.6120385 8.6120385 ZT12-15 9.075409 9.075409 9.075409 ZT16-19 8.7544655 8.7544655 8.7544655 ZT20-23 7.756349 7.756349 7.756349