E-commerce giant amazon announced on Tuesday that it delivered more than 5 billion items globally through its membership service, AmazonPrime, in and said its membership growth hit a record high in 2017.

This is the first time Amazon has announced the number of orders made by its members for a full year, but did not provide 2016 figures for reference.

Meanwhile, Amazon said its Prime members in the U.S. were buying its own Fire TV Stick and its Echo Dot voice-assistant device the most among all product categories.

Amazon's membership service, AmazonPrime, offers free two-day shipping and unlimited access to movies and TV shows online. As a result, Prime has attracted a large number of new and existing subscribers every year.

Last year, AmazonPrime became available for the first time in Mexico, the Netherlands, Luxembourg and Singapore. Prime is now available to Amazon customers in 16 countries