condition mean min max ZT0-3 3.436141666666667 1.458575 5.80557 ZT4-7 1.673585 1.673585 1.673585 ZT8-11 2.2906649999999997 2.2906649999999997 2.2906649999999997 ZT12-15 2.563715 2.36271 2.76472 ZT16-19 5.3173200000000005 5.3173200000000005 5.3173200000000005 ZT20-23 6.617305 6.617305 6.617305