condition mean min max ZT0-3 8.935717 8.935717 8.935717 ZT4-7 8.948557000000001 8.948557000000001 8.948557000000001 ZT8-11 7.1552585 7.1552585 7.1552585 ZT12-15 7.369117 7.369117 7.369117 ZT16-19 7.2353115 7.2353115 7.2353115 ZT20-23 8.086027999999999 8.086027999999999 8.086027999999999