condition mean min max ZT0-3 7.986423 7.986423 7.986423 ZT4-7 8.671021 8.671021 8.671021 ZT8-11 8.544768999999999 8.544768999999999 8.544768999999999 ZT12-15 9.044799000000001 9.044799000000001 9.044799000000001 ZT16-19 7.759704000000001 7.759704000000001 7.759704000000001 ZT20-23 7.738213999999999 7.738213999999999 7.738213999999999