condition mean min max ZT0-3 8.261506 8.261506 8.261506 ZT4-7 8.2817835 8.2817835 8.2817835 ZT8-11 8.595899 8.595899 8.595899 ZT12-15 7.9358615 7.9358615 7.9358615 ZT16-19 8.834161 8.834161 8.834161 ZT20-23 7.557807500000001 7.557807500000001 7.557807500000001