I believe after 29/May you might have re-installed one of the previous (uninstalled) apps, and that traffic (74MB) is now shown next to the specific app. Otherwise, I can't see any reasonable explanation.
Ex.: Before 29/May Google Chrome was uninstalled after it had used 74MB. After 29/May you re-installed it, and now its traffic is shown separately: Google Chrome 74MB (or more, if you used it afterwards).
Never odd or even.