condition mean min max ZT0-3 8.2023925 7.9762450000000005 8.42854 ZT4-7 8.999604999999999 8.999604999999999 8.999604999999999 ZT8-11 7.560309999999999 7.560309999999999 7.560309999999999 ZT12-15 0 0 0 ZT16-19 7.39622 7.39622 7.39622 ZT20-23 9.69276 9.69276 9.69276