Beginners Questions


I'm new to all of this so please bear with me.
I'm in receipt of 100 reports. Each report is the same but is simply taken at a different moment in time.
Within each of these reports is a device and then alongside it is a % value denoting utilisation. I need a way to analyse this data to identify which devices have a utilisation (across all 100 data points) that is within + / - 3% of the first value.
I was thinking of using standard deviation but I'm not sure how to draw conclusions from the value that would produce.
Any suggestion appreciated?