Amazon launched Amazon Prime in 2005 as an all-you-can-eat free two-day shipping alternative on one million items sold online. Now seven years later, the $79 annual service has expanded to include more than 15 million eligible items, access to over 22,000 Prime Instant Videos and more than 180,000 books that are part of the Kindle Owners' Lending Library.

To celebrate the milestone, Amazon has released some fun facts with regards to Prime. Interestingly enough, the free two-day shipping service through Prime is now more popular than the free super saver shipping available to non-Prime members. Super saver shipping launched in 2002 and is available on orders over $25. Alternately,  Prime members also enjoy $3.99 overnight shipping on many items.

Unsurprisingly, the Kindle Fire, the $79 Kindle and the Kindle Touch are the three most popular items purchased using free two-day shipping this year. For what it's worth, the first book in the Fifty Shades of Grey trilogy is fourth.

In any given week, 96.4 percent of the total Prime Instant Video catalog is viewed. The most watched TV show is Downton Abbey Season 1 and the most popular film is The Girl With the Dragon Tattoo. In the Lending Library, Amazon notes that all seven Harry Potter titles are available for check out but the most borrowed title in the history of the service is The Hunger Games.

Do you shop with Amazon and if so, have you signed up for their Prime membership? If not, you can still cash in on a free one-month trial membership to see if it's right for you.