condition mean min max ZT0-3 2.3930499999999997 2.3930499999999997 2.3930499999999997 ZT4-7 1.971355 1.971355 1.971355 ZT8-11 2.183525 2.183525 2.183525 ZT12-15 2.03307 2.03307 2.03307 ZT16-19 2.9824349999999997 2.9824349999999997 2.9824349999999997 ZT20-23 2.230165 2.230165 2.230165