condition mean min max ZT0-3 5.795295 5.795295 5.795295 ZT4-7 4.644245 4.644245 4.644245 ZT8-11 6.329420000000001 6.329420000000001 6.329420000000001 ZT12-15 6.6280850000000004 6.6280850000000004 6.6280850000000004 ZT16-19 6.987525 6.987525 6.987525 ZT20-23 5.1299150000000004 5.1299150000000004 5.1299150000000004