A Costco membership warehouse. Image credit: Wikimedia Commons.

Costco Wholesale (COST 0.17%) continues to parlay its membership warehouse model into impressive growth. While competitors like Wal-Mart (WMT 1.32%) are struggling to compete against the likes of Amazon.com, Costco is building new locations and growing in popularity among existing customers.

This success made Costco the world's second largest global retailer in 2015, with sales of $114 billion. While that's a far cry from the nearly $500 billion in annual revenue earned by Wal-Mart, Costco does so with far fewer locations and is catching up quickly. Over the past three years, Costco's top line has grown at roughly three times the pace of Wal-Mart's.

I recently waded through Costco's regulatory and investor-related filings. Here are 10 numbers that go a long way toward explaining the warehouse giant's success:

1. Costco has 83 million cardholders worldwide, equating to 45 million households.

2. Almost all Costco members renew their memberships -- 91% of members in the U.S. and Canada, and 88% worldwide did so last year.

3. While other retailers struggle to attract traffic to their stores, Costco's members are shopping its warehouses more frequently than ever. Last year, shopping frequency among existing customers increased by 4% compared to 2014.

4. Executive members, who pay twice as much as Gold Star members, represent over one-third of Costco's membership base but account for nearly two-thirds of its sales.

5. Speaking of members, the membership fees make up more than all of Costco's annual profit. In 2015, membership fees added up to $2.6 billion. The company's net income, meanwhile, was only $2.4 billion.

6. Sales of organic products are becoming increasingly popular at Costco, topping $4 billion in 2015.

7. Costco operates 698 warehouses. A large majority are in the United States (488), followed by Canada (90), Mexico (36), the United Kingdom (27), Japan (24), Korea (12), and Taiwan (11), among others.

8. As of calendar 2015 year-end, 490 gasoline stations were in operation.

9. Costco sold 128 million hotdogs last year at its food court. That's purportedly four times as many as major league ballparks sold last year combined.

10. Costco consistently increases the amount of money that it distributes to shareholders. Its dividend growth rate since 2004 is 13% per year. Its first dividend, initiated in 2004, was $0.40 per share per year. Today, it's at $1.60 per year.

Ultimately, Costco's continued success will be based on two things: stocking its stores with attractive and popular products, and offering a great value proposition. The latter is particularly important given that Costco's primary brick-and-mortar competitor, Wal-Mart, is founded on the principal of everyday low prices.

Costco comments on this in its latest 10-K:

Our philosophy is to provide our members with quality goods and services at the most competitive prices. We do not focus in the short term on maximizing prices charged, but instead seek to maintain what we believe is a perception among our members of our "pricing authority" -- consistently providing the most competitive values.

The membership warehouse chain has thus far lived up to this goal, and, for investors looking for a strong and stable company, there seems to be little reason to believe that it won't continue to do so going forward.