If you're an income investor seeking dividend stocks, chances are good your top priority is the safety and stability of that income stream. How much better, though, if that income stream could grow. Below, I've picked three dividend stocks that are playing major, long-term trends -- the sort of demographic tailwinds that should help them print more and more money each year for many years to come.

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Two for the price of one

Welltower (NYSE:HCN) plays on two big trends: the greying of America and the growing push to reduce healthcare costs. With 10,000 baby boomers turning 65 every day from now through 2029, the need for senior care is going to explode in the U.S. Welltower is a big player in this space, with roughly 64% (and growing) of its portfolio net operating income (NOI) generated from senior housing. Roughly 20% comes from long-term post-acute care, with 16% of NOI coming from outpatient medical properties.

Senior care is expected to increase, and Welltower has a big senior-care footprint that's good enough on its own. But with this massive age cohort getting older, there's tremendous interest in reducing healthcare expense by treating people in lower-cost settings. Hospitals are the most expensive settings, while the lowest are... senior housing. Recognizing this opportunity, Welltower plans to shift its portfolio to 70% senior housing by Q4 2016, and hopefully more thereafter.

With a juicy 5.5% dividend yield and a 74% FFO payout ratio, Welltower has plenty of space to continue growing its dividend and invest in more senior-housing opportunities.

More renters

Homeownership rates in the United States have been on the downswing since 2004, sinking to 63.7% last year, according to a study by the Joint Center for Housing Studies at Harvard University. The decline in homeownership can be tied to a number of major trends, but one I'll highlight here is the student debt crisis. With the median amount owed soaring from $10,500 in 2001 to $17,000 in 2013, many young workers are pinched by debt payments. That's preventing many young would-be homeowners from building up the downpayment and debt-to-income ratios that would make lenders willing to give them a mortgage.

The clear beneficiaries: Apartment REITs, like Equity Residential (NYSE:EQR). Equity Residential has focused its resources in six markets where real estate (both single-family and multifamily) is expensive: Boston, New York, Washington, D.C., Seattle, San Francisco, and Southern California. These are also locations with strong growth in high-wage jobs, so people are able to absorb substantial rent increases.

With tremendous housing demand and constrained supply in these markets, Equity is in the driver's seat and has been able to steadily improve its rental metrics. In fact, management predicts that Equity's portfolio will average 96% occupancy throughout 2016. With a 3.4% dividend and a 67% FFO payout ratio, there's plenty to like about Equity Residential.

A note of caution: Equity Residential did recently reduce its quarterly dividend by a few cents in connection with the sale of $5.4 billion worth of property to Starwood Capital Group. But in doing so, management also paid out an $11-per-share set of special dividends. While the regular dividend is going to be volatile (having also been cut in 2009), management is clearly pretty shareholder-friendly given its use of special dividends.

Data, data, data

Do you want to invest in technology, but don't know who's going to win the wearable/smartphone/app/cloud wars? Are you uncomfortable with incredibly expensive start-ups that don't make a profit? Would you rather earn a dividend?

Digital Realty (NYSE:DLR) may be the stock for you. This REIT invests in data centers, which it then leases out to big names in the tech world -- folks like Facebook, LinkedIn, and AT&T. As global connectivity expands, more data centers will be needed, strengthening the demand for Digital Realty's properties and giving the REIT great opportunities to expand its worldwide footprint and margins. (Speaking of which, Digital Realty is expanding internationally, having recently purchased a portfolio of eight data centers in Europe.)

And the underlying debt structure looks good, too. Generally speaking, REITs are subject to interest-rate risk. If the Fed boosts interest rates, they suffer a double whammy: Higher interest rates mean borrowing becomes more expensive, hindering future growth. Higher interest rates also mean that current floating-rate debt becomes more burdensome. Fortunately, Digital Realty has hedged the second part, given that 91% of its debt is at a fixed rate and therefore will not change if interest rates increase. That gives management good debt predictability.

If you see data connectivity as a trend likely to continue and expand, Digital Realty is an attractive play. The business is firing on all cylinders, with management anticipating 20% year-over-year growth in adjusted funds from operations for full-year 2016. Now, its FFO payout ratio is a bit higher than I'd like -- 89% in the trailing 12 months, according to data from S&P Market Intelligence -- but I think future growth opportunities and prudent management of its 3.9% dividend will give Digital Realty a bigger margin of safety in the future.

A rising tide

The beautiful thing about investing in major trends is that the rising tide should hopefully lift most boats. Look for dividend growth among these and other well-run sector plays as those sectors continue their demographically driven march forward.

Michael Douglass has no position in any stocks mentioned. The Motley Fool recommends Welltower. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.