Thanks for the advice. I switched over to streaming and am getting about 25-30 tweets/sec that contain 'rt'.
Based on main website search, I estimate there are about 45-50 tweets/ sec that contain 'rt'. So, I am only getting about 50% of the actual tweets. If I applied for the retweet streaming api, would that give me a higher percentage of the retweets? Or is there another way to increase that percentage? Thanks for your help.