The ratio of sponsored (paid) tweets and original content tweets.
The percentage of your recent tweets that have come from SponsoredTweets versus the tweets that you have sent out that are not Sponsored.
Advertisers are looking for Tweeters that tweet original content and interact with their followers in addition to sending out Sponsored Tweets. A good ratio to strive for is 3 non-sponsored tweets for every Sponsored Tweet you send out – this would be a 25% ratio. This still keeps you very engaged with your followers, without overwhelming them with Sponsored content.
If you ever notice your ratio climb above the 50% mark be sure to spend more time interacting with your audience by tweeting non-sponsored content. Not only will the Advertiser enjoy this, but so will your followers!