condition mean min max ZT0-3 5.482361666666667 4.719375 5.86466 ZT4-7 3.823475 3.823475 3.823475 ZT8-11 3.950235 3.950235 3.950235 ZT12-15 7.7641225 7.7635499999999995 7.764695000000001 ZT16-19 6.234780000000001 6.234780000000001 6.234780000000001 ZT20-23 6.54241 6.54241 6.54241