condition mean min max ZT0-3 7.401685 7.401685 7.401685 ZT4-7 8.953265 8.953265 8.953265 ZT8-11 9.0906555 9.0906555 9.0906555 ZT12-15 9.322237 9.322237 9.322237 ZT16-19 8.391783 8.391783 8.391783 ZT20-23 8.808765000000001 8.808765000000001 8.808765000000001