condition mean min max ZT0-3 6.523936666666667 4.184670000000001 7.905705 ZT4-7 8.189315 8.189315 8.189315 ZT8-11 5.973025 5.973025 5.973025 ZT12-15 7.2691125 6.640605 7.89762 ZT16-19 8.345585 8.345585 8.345585 ZT20-23 9.86148 9.86148 9.86148