condition mean min max ZT0-3 2.981885 2.02674 3.93703 ZT4-7 3.88281 3.88281 3.88281 ZT8-11 2.71235 2.71235 2.71235 ZT12-15 0 0 0 ZT16-19 7.268745 7.268745 7.268745 ZT20-23 11.7811 11.7811 11.7811