condition mean min max ZT0-3 16.881069 16.881069 16.881069 ZT4-7 18.55975 18.55975 18.55975 ZT8-11 17.6873825 17.6873825 17.6873825 ZT12-15 17.583043500000002 17.583043500000002 17.583043500000002 ZT16-19 14.5625955 14.5625955 14.5625955 ZT20-23 18.9399485 18.9399485 18.9399485