condition mean min max ZT0-3 8.22303 8.22303 8.22303 ZT4-7 7.034776 7.034776 7.034776 ZT8-11 6.6871005 6.6871005 6.6871005 ZT12-15 6.9593615 6.9593615 6.9593615 ZT16-19 7.170946000000001 7.170946000000001 7.170946000000001 ZT20-23 7.101276 7.101276 7.101276