Personally, what I like to do is schedule a report to be run on a regular basis (daily or weekly depending on the volume) and dump all the data into excel.
Then you can easily graph trends by keywords, ad group, etc to visualize the data.
Also, if you keep those reports, you can start to narrow down timeframes when something went strange that you might not have initially noticed.
Placement / Keyword Performance
Unit of time Monthly. You could set that to daily.
I manually selected the ad group I wanted to see for. Quality Score is checked by default. You can change it around to show as much or as little information you want.
This gave me a list of keywords I then clicked on quality score so that it listed them from highest to lowest. This way I could see what my highest quality score was ever. I can then order it by keyword then I could see them in order of month. You could then export that report and get real fancy with it.
