condition mean min max ZT0-3 8.71574 8.71574 8.71574 ZT4-7 7.956481500000001 7.956481500000001 7.956481500000001 ZT8-11 8.4512165 8.4512165 8.4512165 ZT12-15 8.9159445 8.9159445 8.9159445 ZT16-19 8.07018 8.07018 8.07018 ZT20-23 7.6630515 7.6630515 7.6630515