Led by single-track downloads, worldwide digital music sales reached $2.9 billion in 2007, up almost 40% from the previous year, according to a new publication issued by the IFPI.

Digital formats now account for roughly 15% of the global music market, up from 11% in the previous year, the trade body notes in its 2008 "Digital Music Report," released today. Nowhere is the impact of digital music's presence felt more than in the United States and South Korea. In the U.S., 30% of all recorded music sold is from online or mobile sources, while in South Korea, more than 60% of the market is created by digital formats.

While the underlying tone of the report is one of promise for the digital arena, the IFPI and its chairman/CEO John Kennedy call for greater involvement from governments and ISPs in playing a "responsible role" in curtailing digital piracy.

Kennedy identifies French president Sarkozy's November 2007 initiative drawing on cooperation from ISPs in tackling piracy as "the most significant milestone yet" in the battle against online piracy.

"The last year has finally seen the wind of change blowing through old assumptions about the role Internet service providers should play in protecting copyrighted content. ISP responsibility is becoming an accepted idea," Kennedy says in the report's introduction.

And on the role of government in future, he notes, "In Europe, we look to the European Union to capitalise on the momentum created by the Sarkozy Agreement. The moment for EU legislation to be drawn up has already arrived."

Under the strapline "Revolution, Innovation, Responsibility," the report notes more than 500 legal download services currently operate, and more than 6 million titles are now available through those services.

An inaugural global download sales chart is published in the report, topped by Avril Lavigne's "Girlfriend (RCA)," which sold 7.3 million tracks through the year. The global digital market is split roughly 50/50 between online and mobile sales.