LinkedIn, the social networking site for business professionals, announced Wednesday that it has reached 50 million users worldwide. 

In a post on the company’s blog, LinkedIn CEO Jeff Weiner said that while it took the social network more than a year to reach one million users after its founding in 2003 - it took only 12 days to attract the last million users to reach this new milestone.

Weiner said that half of LinkedIn's user base resides outside of the US, with approximately 11 million users in Europe and three million in India. He also noted that the Netherlands has the highest rate of per-capita adoption outside of the US, at 30%.

Although LinkedIn lacks the high-profile popularity of Facebook, which recently reached 300 million users, and upstart Twitter, the company is further along in creating a stable business model based on advertising, subscriptions, and sales, according to MediaPost.

LinkedIn, which has reportedly been profitable for the past few years, was valued at about $1 billion during its latest round of financing in June 2008. The company does not have any immediate plans to go public, LinkedIn founder Reid Hoffman said last month.