condition mean min max ZT0-3 7.215315 7.215315 7.215315 ZT4-7 6.752675 6.752675 6.752675 ZT8-11 5.9744 5.9744 5.9744 ZT12-15 7.2767 7.2767 7.2767 ZT16-19 9.40554 9.40554 9.40554 ZT20-23 8.18442 8.18442 8.18442