condition mean min max ZT0-3 1.592144862 0.5747096070000001 2.609580117 ZT4-7 4.6654485195 4.2345658754999995 5.0963311635 ZT8-11 6.30354643125 5.426110409 7.1809824535 ZT12-15 7.92579670225 7.4884295335 8.363163871000001 ZT16-19 7.18638146825 6.6923141255 7.680448811 ZT20-23 9.878649067 8.364336499 11.392961634999999