Is 26.38 Gt a lot?

There's 91k cubic kilometers of fresh water in lakes according to: https://www.usgs.gov/special-topics/water-science-school/sci...

And a cubic kilometer is basically a Gt, right? .98 Gt?

So 26 / 91,000 = ~0.02% ?

Is that a lot? If it's really 0.02% - wouldn't you expect something to be random noise? How do we know it's not random noise?