condition mean min max ZT0-3 8.801545 8.801545 8.801545 ZT4-7 8.475265 8.475265 8.475265 ZT8-11 9.111699999999999 9.111699999999999 9.111699999999999 ZT12-15 7.6871100000000006 7.6871100000000006 7.6871100000000006 ZT16-19 9.443670000000001 9.443670000000001 9.443670000000001 ZT20-23 6.841455 6.841455 6.841455