condition mean min max ZT0-3 8.362925 8.362925 8.362925 ZT4-7 8.54828 8.54828 8.54828 ZT8-11 8.205492 8.205492 8.205492 ZT12-15 8.135132500000001 8.135132500000001 8.135132500000001 ZT16-19 7.963338 7.963338 7.963338 ZT20-23 8.168806 8.168806 8.168806