There aren't many health insurance companies that pay dividends. And among those that do, some don't pay out very much.

However, Aetna (NYSE:AET) Anthem (NYSE:ANTM), and UnitedHealth Group (NYSE:UNH) -- three of the largest health insurers in the nation -- do reward shareholders with solid payouts. Here's why they rank as the top dividend stocks in health insurance. 

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Aetna

Aetna serves nearly 47 million individuals, though over 23 million members' health insurance policies. In 2016, Aetna reported revenue of nearly $63.2 billion and earnings of almost $2.3 billion. 

It's stock dividend currently yields 1.38%. Earlier this year, Aetna doubled its dividend payment, and with a payout ratio of only 22%, it appears to be in good position to increase its dividend further. Shareholders are also being rewarded through share buybacks. Aetna's board of directors approved a stock repurchase plan totaling $4 billion in February and quickly began buying back shares.  

Aetna greatly reduced its participation in state Obamacare exchanges in 2017. While that will cause revenues to fall, it should increase profits. Over the next five years, Wall Street analysts project the company will grow earnings by an average annual rate of nearly 12%.

Anthem

Anthem is an independent licensee of the Blue Cross and Blue Shield Association with over 40 million medical members. The company reported revenue of $84.9 billion last year, with earnings of $2.5 billion.

Anthem has increased its dividend in the last couple of years, and its yield now stands at 1.43%. More dividend hikes could be in store, since the health insurer -- like Aetna -- currently uses only 22% of its earnings to fund those payouts. Unlike Aetna, however, Anthem has not actively bought back shares over the past year.

Anthem is one of the largest health insurers that still offer plans on the Obamacare exchanges. However, the company is still mulling whether it will continue to participate in 2018. For now, analysts think Anthem will grow its earnings by more than 11% annually over the next few years. That estimate could change based on what the company does regarding its Obamacare participation. 

UnitedHealth Group

UnitedHealth Group serves more than 49 million medical members and ranks as the largest health insurer in the U.S. The company reported revenue totaling $184.8 billion, with earnings of more than $7 billion.

Like Anthem, UnitedHealth claims a dividend yield of 1.43%. However, the big health insurance company has a better track record of dividend hikes, raising its dividend for the last seven years. With a payout ratio of less than 26%, UnitedHealth Group should be able to continue that streak into the future. The company has also frequently repurchased shares, with 47 million shares remaining to be purchased as of March 31, 2017, under the current authorization.

UnitedHealth reduced its participation to only three Obamacare state exchanges this year after incurring steep losses. As was the case with Aetna, this pullback reduced UnitedHealth's revenue from individual plans, but it also helped improve overall profitability. The consensus among Wall Street analysts is that UnitedHealth Group will grow earnings by an average annual rate of nearly 15%.

Best pick

Overall, UnitedHealth Group appears to be the best dividend stock in health insurance. The company claims the highest dividend yield and best track record of dividend increases. In addition, UnitedHealth appears to be poised to grow earnings faster than its peers.

A key factor behind UnitedHealth Group's strong growth prospects is its Optum business segment. This unit provides pharmacy benefits management, technology, and other healthcare-related services to customers. Optum is also highly profitable. Last year, it generated less than 20% the company's total revenue, but contributed more than 47% of total earnings before income taxes.

Keith Speights has no position in any stocks mentioned. The Motley Fool recommends UnitedHealth Group. The Motley Fool has a disclosure policy.