Who I have the same questioned this topic

How do you track which apps are using the most data? I just switched from a Droid 4 to the S4 and received a notice that over 75% of my data has been used in under 3 weeks. I never received this notice before so it much be some of the apps that came on the phone, which is very annoying to me, why would they automatically install apps that use so much data? Any tips would be appreciated. Thank you.