Why does the mean on my Calibration Report not match the raw data from my calibration service?

The four individual measurements are raw measurements that are converted from grams to uL, and the mean value that you see is not calculated based on the raw data alone. 

Because we are an ISO 17025 accredited facility, we take environmental variables such as temperature, pressure, relative humidity, and evaporation rate into account when calculating the final mean volume, which provides a more accurate estimate of the true mean value.