From the Pew article, Though not especially productive in passing bills, the 116th Congress set new marks for social media use, by Aaron Smith and Sono Shah (1/25/2021):
Voting members of the 116th Congress collectively produced more than 2.2 million tweets and Facebook posts in 2019 and 2020. That means the median member of Congress produced more than 3,000 posts across their profiles on the two social media platforms during this span.
The 3000 sound like a lot but amounts to only about 8 posts a day and I have to imagine that some of it is done by aides.
There are two other charts in the article and a detailed methodology section. There is also a link to a related article which includes the number of laws passed from the 101st through 116th congress.
