condition mean min max ZT0-3 7.842585 7.842585 7.842585 ZT4-7 5.900235 5.900235 5.900235 ZT8-11 5.61448 5.61448 5.61448 ZT12-15 6.695055 6.695055 6.695055 ZT16-19 9.24445 9.24445 9.24445 ZT20-23 9.092005 9.092005 9.092005