motivated by a discussion on Bogleheads
Yahoo (sometimes) has dividends and one can download 'em to an Excel spreadsheet, like so:
You type in a bunch of Yahoo stock symbols (up to 30 of 'em), some Dates ... then click a button.
You get a bunch of historical dividends, the latest stock price and some "percentage".
That percentage is the (Sum of Dividends) as a "percentage" of the (Stock Price).