condition mean min max ZT0-3 2.266894 1.723968 2.80982 ZT4-7 1.8681100000000002 1.8681100000000002 1.8681100000000002 ZT8-11 3.15756 3.15756 3.15756 ZT12-15 0 0 0 ZT16-19 11.044640000000001 11.044640000000001 11.044640000000001 ZT20-23 6.13685 6.13685 6.13685