Using R to find frequency a tweeter uses exclamation marks in their tweets?


For a list of users, what is the best way to find the number of times a user uses exclamation marks in their tweets. At the moment I’m thinking of using userTimeline to create a data frame for each user then having r count the number of exclamation marks in the tweets, but I have to do this for over 600 users and I’m wondering if there is a more efficient way to do this?