Conversation so far:
who is elected for a six year term
Senators serve six year terms.
what is the age qualification to run for Senator
To be a Senator, a person must be aged 30 or over
does the candidate for senator have to be a us citizen
Candidates for U.S. Senator must have been U.S. citizenship for at least nine years before running.

Question: how many (of the) politicians have been expelled
Self-contained rewrite: how many senators have been expelled in the senate's history