condition mean min max ZT0-3 2.408614 1.652993435 3.164234565 ZT4-7 5.01908838175 4.2069468809999995 5.8312298825 ZT8-11 7.5561423625 6.0296929514999995 9.0825917735 ZT12-15 8.35311808575 8.0787266295 8.627509541999999 ZT16-19 7.199312024249999 6.739108935999999 7.659515112499999 ZT20-23 9.1982192485 9.0239810265 9.372457470499999