condition mean min max ZT0-3 7.940441 7.940441 7.940441 ZT4-7 8.9940555 8.9940555 8.9940555 ZT8-11 9.306627 9.306627 9.306627 ZT12-15 7.7848735 7.7848735 7.7848735 ZT16-19 8.988199999999999 8.988199999999999 8.988199999999999 ZT20-23 8.6927855 8.6927855 8.6927855