Google Takeout lets you download an archive of your data from various Google products. I downloaded my Gmail archive as an mbox file and visualized all of my personal Gmail account traffic since signing up back in July 2004. This analysis excludes work and school email traffic (as well as my other Gmail account for signing up for web sites and services), as I have separate dedicated email accounts for each. It also excludes the Hangouts/chats that Google includes in your mbox archive. So, this analysis just covers personal communication.
This also demonstrates working with time series in Python and pandas. All of my code is on GitHub as an IPython notebook. You can re-purpose it for your own inbox – just download your Gmail archive then run my code.