I found a solution that I think is better than your Excel spreadsheet called CheatSheet. Press and hold the command key (⌘) and it displays the shortcuts for the app, any app, that currently has the focus. It never goes out of date because it reads the shortcuts in the app itself when it is activated. 😎

By-the-way CitiCard and others have switched to sending entirely new numbers because with only 4 digits it takes a computer only seconds to determine your new number. CitiCard is protecting you and themselves from financial loss.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein