Reuters has a stock search tool. They list 8914 US companies, 2653 of which have an Indicated Annual Dividend [1] greater than zero, and 2645 have a Dividend Yield [2] greater than zero. So about 30%.

[1] Indicated Annual Dividend: The total of the expected dividend payments over the next twelve months. It is generally the most recent cash dividend paid or declared multiplied by the dividend payment frequency, plus any recurring extra dividends.

[2]Dividend Yield: This value is the current percentage dividend yield based on the present cash dividend rate.