By the numbers: Comparing the Mueller investigation to past probes

Left: Special Prosecutor Kenneth Starr. Photo: David Hume Kennerly/Getty Images. Right: Special Counsel Robert Mueller. Photo: Alex Wong/Getty Images

Special counsel Robert Mueller is one year in to his investigation of President Trump's presidential campaign and potential meddling by the Russian government, only a blip compared to the length of other major political investigations, FiveThirtyEight reports.

The big picture: One year later, we're still unsure of the scope of what Mueller does or doesn't know, and as noted by FiveThirtyEight, predicting the outcome of an investigation so early on hasn't proven to be useful in the past.