condition mean min max ZT0-3 6.787051 6.787051 6.787051 ZT4-7 6.944837 6.944837 6.944837 ZT8-11 6.804551 6.804551 6.804551 ZT12-15 7.1615285 7.1615285 7.1615285 ZT16-19 7.8081084999999995 7.8081084999999995 7.8081084999999995 ZT20-23 7.848290500000001 7.848290500000001 7.848290500000001