condition mean min max ZT0-3 8.194115 8.194115 8.194115 ZT4-7 7.59164 7.59164 7.59164 ZT8-11 7.50559 7.50559 7.50559 ZT12-15 8.206675 8.206675 8.206675 ZT16-19 9.734905000000001 9.734905000000001 9.734905000000001 ZT20-23 8.39507 8.39507 8.39507