It sounds to me like your data has been sampled.
samplingLevel string no The desired sampling level. Allowed Values:
•DEFAULT — Returns response with a sample size that balances speed and accuracy. •FASTER — Returns a fast response with a smaller sample size. •HIGHER_PRECISION — Returns a more accurate response using a large sample size, but this may result in the response being slower.
Note: If I remember right the API should return some variable with your data. It tells you that the data was sampled: try looking for something like containsSampledData, sampleSize, or sampleSpace. I cant remember which one it is right this minute.