condition mean min max ZT0-3 7.514383 7.514383 7.514383 ZT4-7 8.220738 8.220738 8.220738 ZT8-11 7.8033465 7.8033465 7.8033465 ZT12-15 7.119661 7.119661 7.119661 ZT16-19 8.6352735 8.6352735 8.6352735 ZT20-23 8.489974 8.489974 8.489974