condition mean min max ZT0-3 6.94034 6.94034 6.94034 ZT4-7 4.74237 4.74237 4.74237 ZT8-11 6.624105 6.624105 6.624105 ZT12-15 7.41355 7.41355 7.41355 ZT16-19 10.01877 10.01877 10.01877 ZT20-23 7.357095 7.357095 7.357095