condition mean min max ZT0-3 15.806375 13.8943 17.71845 ZT4-7 11.0857 11.0857 11.0857 ZT8-11 12.1377 12.1377 12.1377 ZT12-15 0 0 0 ZT16-19 23.9389 23.9389 23.9389 ZT20-23 21.80995 21.80995 21.80995