condition mean min max ZT0-3 13.431916508 12.105175346 14.75865767 ZT4-7 6.623474187999999 6.1607977295 7.0861506465 ZT8-11 4.965655898 4.6631084285 5.2682033675 ZT12-15 5.7475667205 5.1679535665 6.3271798745000005 ZT16-19 10.22426364225 8.6304593355 11.818067949 ZT20-23 20.938244275 17.995076349999998 23.8814122