condition mean min max ZT0-3 11.5776825 9.347315 13.80805 ZT4-7 18.673499999999997 18.673499999999997 18.673499999999997 ZT8-11 24.8249 24.8249 24.8249 ZT12-15 0 0 0 ZT16-19 36.4002 36.4002 36.4002 ZT20-23 23.07465 23.07465 23.07465