The secret to Chick-fil-A's success is as simple as saying "please" and "thank you."

The chicken chain is statistically the most polite chain in the restaurant business, according to a QSR Magazine's annual drive-thru report released in October.

Employees at Chick-fil-A were the most likely of the 15 chains surveyed to say "please" and "thank you," and to smile at drive-thru customers. Chick-fil-A workers were also as the second most likely to have a "pleasant demeanor," only topped by the up-and-coming fast-food chain PDQ.

According to the report, Chick-fil-A employees said "thank you" in 95.2% of drive-thru encounters, based on data from nearly 2,000 visits to 15 restaurant chains.

For comparison, KFC had a "thank you" rate of 84.9%. McDonald's rate was 78.4%, putting it in 14th place out of the 15 chains analyzed.

"It’s all about speed and accuracy, but we know our customers appreciate that we can be nice while being fast and accurate," Mark Moraitakis, senior director of hospitality and service design, told QSR. "Eye contact and smiling go a long way in the drive-thru experience."

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Chick-fil-A has taken pains to make its drive-thru strategy as customer-friendly as possible, reports QSR. The chain has dedicated drive-thru teams, made up of compatible Chick-fil-A employees, and sends employees with tablets out to the drive-thru lane to take orders when lines begin to form.

While small pleasantries are easy to dismiss in the multi-billion dollar restaurant business, these little things have played a key role in setting Chick-fil-A apart from the competition.

In 2015, Chick-fil-A generated more revenue per restaurant than any other fast-food chain in the US. The chain's average sales per restaurant reached nearly $4 million.

Meanwhile, the average KFC sold $1 million in 2015.

Analysts have said that customer service is key to Chick-fil-A's success. Superior customer service drives higher sales per unit, contributing to the chain's ability to generate greater revenue than chains such as KFC, Pizza Hut, and Domino's with more than twice as many US locations.

According to Chick-fil-A, the chain has the upper hand when it comes to customer service because it invests more than other companies in training its employees. The chicken chain's unique business structure, in which each franchisee is only allowed to open one Chick-fil-A location, further allows for more hands-on supervision and training.