condition mean min max ZT0-3 5.051976666666667 4.444315 5.689015 ZT4-7 6.53183 6.53183 6.53183 ZT8-11 4.979089999999999 4.979089999999999 4.979089999999999 ZT12-15 6.2250499999999995 6.17528 6.27482 ZT16-19 5.8967849999999995 5.8967849999999995 5.8967849999999995 ZT20-23 5.86985 5.86985 5.86985