Inform about the number of observations

To compute a confidence interval or determine if there is a statistical difference between two versions, at least three pieces of information is required:

• the mean
• the standard deviation (or variance)
• the number of observations, that the mean and standard deviation were sampled from.

The number of observations is not really clear from the output.

In a previous conversation @mcollina wrote:

The approach that autocannon takes is that it samples once per second the number of requests that happened within that second (https://github.com/mcollina/autocannon/blob/master/lib/run.js#L119-L122). So, it's 30 samples.

It is not really clear to me how that data is aggregated. Or how it relates to 30 samples.