condition mean min max ZT0-3 2.772275 2.29326 3.25129 ZT4-7 5.89043 5.89043 5.89043 ZT8-11 6.747755 6.747755 6.747755 ZT12-15 0 0 0 ZT16-19 7.20761 7.20761 7.20761 ZT20-23 5.06968 5.06968 5.06968