Feature Request: It'd be helpful to see what bigrams are consistently problematic

[psxndc]

I'm ever working to increase my speed and accuracy, but I'm stuck and don't know where to direct my energy. As I go through the exercises, I find that I keep making the same mistakes, e.g., I'll type "re" when I'm supposed to type "er". But I can only catch and process those in the moment, which causes me to lose my flow.

It'd be nice at the summary screen to see some form of "you typed 're' instead of 'er' 17 times out of 28" or something similar and have 3 or 4 of those ranked so I could really focus in on the most problematic bigrams.

Just a thought. Really love Colemak Club, especially the support for DH and the ortho layout. Thanks!