i forgot how it is computed, but you can check the formula. at cell level, the value should be the total amount of bytes transfered on the whole cell (sum of PDCH RLC bytes) per hour.
At cell zone, the aggregation could be wrong. It should be an average aggregation,not a “sum”.
the throughput per cell is not very useful anyway (imo), perhaps it can be used to dimension the abis (but I know better indicators for that).