condition mean min max ZT0-3 14.704313 14.704313 14.704313 ZT4-7 17.042186 17.042186 17.042186 ZT8-11 19.6152575 19.6152575 19.6152575 ZT12-15 22.5205265 22.5205265 22.5205265 ZT16-19 26.248134999999998 26.248134999999998 26.248134999999998 ZT20-23 41.3021045 41.3021045 41.3021045