Anki Stats

Anki is my flashcard program of choice. It outputs a lot of stats:


The above image was generated by Anki itself. I also produce my own Anki stats. It's relatively easy to do. The data file is an SQLite database. I opened it in the SQLite Database Browser and exported the main tables as text files. Then I linked those text files to an MS Access database, set up a few queries, pasted their results to Excel, and created some graphs.
I've organized my Anki cards with tags. The following graph shows the growth of each top-level tag through time. Vertical portions show wholesale import of cards.
This is another way to organize the same data. I grouped all of my European language cards into the eu category in order to compare it with the Chinese (zh) and miscellaneous categories. I use the miscellaneous tag for non-vocabulary cards. 

 This is the 50-day moving average of the percentage of reviews failed:

 This is the 50-day moving average of the percentage of all of my cards that I studied each day:

And finally, the 50-day moving average of the number of reviews done each day: