condition mean min max ZT0-3 15.718986087249998 5.6479468445 25.79002533 ZT4-7 5.404935011 4.776151469 6.033718553 ZT8-11 8.99643513575 8.098095102999999 9.8947751685 ZT12-15 11.5935776325 11.37683543 11.810319835 ZT16-19 12.423099345 11.695239025 13.150959665 ZT20-23 16.081653457500003 14.392375855000001 17.770931060000002