"Total" values in the Calculate area of Charts

We’re starting to dig into metrics reporting in RT to get a better understanding of how well our department functions. We’ve been looking at the reports you can get with the “Calculate” section of the Charts feature & it’s very insightful. In most cases, it’s determining how you want the ticket information grouped together to get the most meaningful results. My question regards the “Total” at the bottom: https://docs.bestpractical.com/rt/4.4.1/charts.html#Calculated-Values

Is that row the sum of all the column data above it? We have one report we ran where the total time came out to 17 years+, but based on the column data it should have been higher. It’s also possible I’m displaying/reporting the information incorrectly. Thanks!