See which ballots (if any) a question appeared on across GSS years
Details
What ballots did a particular question appear on in each GSS year?
Columns returned are - `variable` Variable name - `year` GSS year - `iap` Numbers in this column mean the question wasn't asked _or_ the ballot system was not in use. - `ballot a`, `ballot b`, etc: Count of the n respondents on each ballot for a particular year.