With interest rates at historical lows, high quality dividend paying stocks are back in vogue. Having been left for dead in the late ‘90s in favor of so-called growth stocks, today’s investor seeks the benefit of knowing that, even if the market is bouncing up and down wildly like an NFL cheerleader, those dividend checks will remain as steady as Tom Brady under pressure.

While it took an internet bubble burst along with a global financial crisis for many to realize the benefit of owning high quality dividend paying stocks, the fact is that over the very long term (namely over the last 100 plus years), dividends have been the source of nearly half of the stock market’s total returns. To put that in perspective, if stocks on average have provided returns of around 9% per year, dividends account for nearly half of that.

Companies like Coca Cola, Johnson and Johnson, McDonalds and others have consistently paid dividends every 90 days for decades on end, and those profits have come during good times and bad. Even during the ‘lost decade’ (appropriately known as the ‘00s) when the US markets went essentially nowhere for a ten year period, dividends for many profitable international companies rose nearly 10% per year on average.

In fact, over many time periods and in most market conditions (the internet boom of the late ‘90s being a rare exception), dividend paying stocks out perform their non-dividend paying (a.k.a. growth stocks) brethren.

The question becomes: which dividend paying stocks are the best? Your first reaction may be that if dividend yields are good, more dividend yields are even better! If one stock pays a 4% dividend and another 7%, the one paying 7% must be a better deal, right?

Well, as with all things in life, sometimes there is such a thing as too much of a good thing. In the case of dividend yields, companies that pay out too muchof their income in the form of dividends could ultimately be an inferior investment over time compared to those who keep some of their profits to reinvest in their business.

So where is the sweet spot? There is an important statistic (oh no, not the word statistic…bear with me, this is an easy one) that will help you determine if the company has the ability to keep paying its dividend over time. It is called the “payout ratio”. It is simply the company’s dividend per share divided by the company’s earnings per share.

For example, if a company pays dividends of $2.00 per share ($0.50 per quarter) and earns $4.00 per share, its payout ratio is 50%. A consistent payout ratio under 70% suggests that the company can continue to make its dividend payouts. If the ratio creeps up north of 80%, and certainly if it exceeds 100%, then there is a risk that the dividend will need to be cut. If this occurs, you get the double whammy of less income arriving to your bank account each month and a likely declining stock price (since investors hate it when companies cut their dividends).

Sure, the government can spend more than it takes in, but companies cannot forever pay more in dividends than they earn in income. That is why the payout ratio is such an important metric for determining the sustainability of a company’s dividend.

There is something comforting and satisfying about receiving a check every 90 days from the companies in which you have invested. Even with the stock market bleeding red as it did during volatile periods in 2011, strong companies kept sending dividend checks quarterly to their investors. Consider making dividend-paying companies a core part of your portfolio.

Do your research – or work with someone who knows the ins and outs of dividend paying stocks – to ensure that those checks keep flowing.