condition mean min max ZT0-3 15.368966666666667 11.3113 17.448 ZT4-7 8.128265 8.128265 8.128265 ZT8-11 9.639605 9.639605 9.639605 ZT12-15 20.30505 19.89575 20.71435 ZT16-19 18.135150000000003 18.135150000000003 18.135150000000003 ZT20-23 26.06665 26.06665 26.06665