condition mean min max ZT0-3 4.742905 4.463620000000001 5.02219 ZT4-7 8.998015 8.998015 8.998015 ZT8-11 11.977015 11.977015 11.977015 ZT12-15 0 0 0 ZT16-19 13.16855 13.16855 13.16855 ZT20-23 11.1065 11.1065 11.1065