condition mean min max ZT0-3 14.175383333333333 13.67135 14.83645 ZT4-7 13.219999999999999 13.219999999999999 13.219999999999999 ZT8-11 15.5394 15.5394 15.5394 ZT12-15 24.502625000000002 23.884900000000002 25.120350000000002 ZT16-19 17.724600000000002 17.724600000000002 17.724600000000002 ZT20-23 19.3592 19.3592 19.3592