New data confirms that Twitter's population is disproportionately black.

According to Edison Research's annual report on Twitter, black people represent 25% of Twitter users, roughly twice their share of the population in general.

Why is this? A few ideas:

• Black people (and Hispanics) are much more likely to access the Internet from mobile devices. Twitter is well-suited to mobile use, and its users are more engaged with the mobile Internet than the general population by a wide margin.
• More black than white celebrities are active Twitter users; Shaquille O'Neal, Oprah, 50 Cent, and P Diddy are all among the most followed accounts on Twitter. That's great publicity for Twitter, and could be helping Twitter become more mainstream among black people.
• The median age for black Americans (according to the 2000 census) is 30 years old, a full seven years younger than for white Americans. Black people therefore make up a relatively higher percentage of the population within the most relevant age groups -- Twitter is most popular amongst 25-34 year-olds.

Those are the best explanations we can come up with. Any thoughts?