condition mean min max ZT0-3 935.193595 935.193595 935.193595 ZT4-7 990.3845635 990.3845635 990.3845635 ZT8-11 585.3478789999999 585.3478789999999 585.3478789999999 ZT12-15 554.171279 554.171279 554.171279 ZT16-19 542.499071 542.499071 542.499071 ZT20-23 523.0796665 523.0796665 523.0796665