condition mean min max ZT0-3 12.359957 12.359957 12.359957 ZT4-7 12.3559275 12.3559275 12.3559275 ZT8-11 13.7244065 13.7244065 13.7244065 ZT12-15 14.7358855 14.7358855 14.7358855 ZT16-19 16.091011 16.091011 16.091011 ZT20-23 16.203727 16.203727 16.203727