condition mean min max ZT0-3 14.290467 14.290467 14.290467 ZT4-7 11.0738315 11.0738315 11.0738315 ZT8-11 10.5014525 10.5014525 10.5014525 ZT12-15 9.323346 9.323346 9.323346 ZT16-19 9.6059585 9.6059585 9.6059585 ZT20-23 9.079039000000002 9.079039000000002 9.079039000000002