Music streaming service Spotify is still yet to launch in the U.S., but it already has big ambitions for revolutionising the market there.

Buried in its annual report, in an interview with CEO Daniel Ek, the IFPI industry umbrella says: “In the U.S., Spotify’s goal is to increase the number of subscribers to a music service by a factor of five”. Ek: “This is obviously a huge task and might take a couple years to reach.”

The target is particularly interesting because Rhapsody, perhaps Spotify’s biggest Stateside rival, saw its subscriber base fall by 50,000 to 700,000 between June and September. Indeed, Spotify is challenged because…

—Rhapsody and eMusic already have strong local U.S. followings.
—U.S. labels are reportedly more concerned that Spotify be premium-only rather than freemium.
—It’s possible Apple (NSDQ: AAPL) may augment iTunes’ a la carte download offering with a web subscription service built on its Lala acquisition.

But converting those occasional, individual MP3 buyers in to dependable, monthly subscribers - like with a mobile carrier or cable TV - could begin to return significant value to the music industry. Music sales in Spotify’s native Sweden bounced back to the tune of 10.2 percent in 2009 - a jump that’s credited to the popularity of streaming services like Spotify itself. Spotify’s user experience is sumptious.

Spotify, which is believed to have given equity to labels for favourable licensing terms, may keep many of its stats close to its chest - but Universal Music Group’s international digital SVP Rob Wells, speaking at IFPI’s report launch in London this morning, wasn’t so shy, adding more data to what we know so far (via speaking to Telegraph.co.uk and BBC News)...

• Spotify was #4 on UMG’s 2009 list of digital revenue generators for it (outside north America).
• “Rob Wells says Spotify now has 250,000 subscribers around the world”.
• “Spotify only needs to convert 10 to 12 percent ... in to having subscriptions ... to make enough money to pay the record labels.” Wells: “That to me equates to a sustainable business model.”
• In the UK and Spain Spotify is paying for every streamed song.
• But in Sweden, Norway, Finland and France, Spotify “pays the record labels from the money generated by subscriptions and advertising and not on a per-stream basis”.
• But it’s “lagging behind” in the UK and Spain, where it’s very popular, because its popularity there means higher and higher outgoings.”

For the record, Spotify itself currently claims nearly seven million users across Europe, and “hundreds of thousands of subscribers”, telling paidContent:UK: “We are currently the biggest music subscription service in Europe.”

The outfit has about 110 staff, split mostly between London and Stockholm, but has been seeking U.S. execs. It has about 6.5 million tracks (that’s about two thirds of all those available). “Our aim has been to do something that consumers love and then figure out how to monetise it,” Ek told IFPI.

I will be reporting from the Midem music industry conference this weekend…

• Spotify’s Ek Thinks Big: Packaged Service Promises ‘A Trillion Transactions’