condition mean min max ZT0-3 23.507766 23.507766 23.507766 ZT4-7 37.139805499999994 37.139805499999994 37.139805499999994 ZT8-11 30.4852435 30.4852435 30.4852435 ZT12-15 31.414086 31.414086 31.414086 ZT16-19 20.300235999999998 20.300235999999998 20.300235999999998 ZT20-23 16.2659425 16.2659425 16.2659425