condition mean min max ZT0-3 32.154486 32.154486 32.154486 ZT4-7 35.8065495 35.8065495 35.8065495 ZT8-11 40.555075 40.555075 40.555075 ZT12-15 28.4844515 28.4844515 28.4844515 ZT16-19 23.6397745 23.6397745 23.6397745 ZT20-23 20.354643 20.354643 20.354643