condition mean min max ZT0-3 1.254537 1.254537 1.254537 ZT4-7 1.2445249999999999 1.2445249999999999 1.2445249999999999 ZT8-11 1.6723750000000002 1.6723750000000002 1.6723750000000002 ZT12-15 1.351352 1.351352 1.351352 ZT16-19 1.7836100000000001 1.7836100000000001 1.7836100000000001 ZT20-23 1.5277176666666668 1.5277176666666668 1.5277176666666668