Do you actually tweet from your Twitter account?

I recently read an article about Twitter users' engagement and I was wondering:
How many of you do you actually tweet from your Twitter account?

According to the WSJ Digits article, nearly 1 out of 2 accounts has never sent a tweet.

A report from Twopcharts, a website that monitors Twitter account activity, states that about 44% of the 974 million existing Twitter accounts have never sent a tweet.

Personally, I use Twitter strictly as a news feed and have never tweeted/retweeted something and I'd bet that most people in the finance community tend to use Twitter this way.

However, as the article correctly mentions, users who actually tweet from their accounts are valuable for the company, since their tweets help generate advertising revenue.

To be sure, people don’t have to actively tweet to find the service useful. There’s more than enough stuff to read on almost any topic in the world on Twitter to keep users occupied.

But having engaged users–those who are active participants in the online conversation–are particularly valuable to Twitter. For one thing, activity tends to make users more inclined to continue using the service.

Secondly, user tweets, retweets, favorites and other actions help Twitter generate advertising revenue. Over the last year, the company has made it easier for users to do those things and introduced user-friendly features such as pictures into the timeline.

So, what do you guys do? Do you send tweets on a regular basis? Or do you use the service just to keep up with the news?