condition mean min max ZT0-3 8.999857 8.999857 8.999857 ZT4-7 9.90127 9.90127 9.90127 ZT8-11 8.827406 8.827406 8.827406 ZT12-15 9.251399 9.251399 9.251399 ZT16-19 9.5317565 9.5317565 9.5317565 ZT20-23 9.427754499999999 9.427754499999999 9.427754499999999