Until 200, there was little or no trend for any of them. Since 2000, Senators and members of Congress have dropped substantially, governors and state officials have dropped by a more moderate amount, and local officeholders have stayed about the same.
Then there are occupations that I classed as "related to politics": lobbyists and several different types of journalists.
For the journalists, it seems to be a pretty steady downward trend since the 1970s. Lobbyists are rated much lower, and there is no change over the decade for which the question has been asked.
Then some business occupations:
Bankers and stockbrokers declined in 2008 and have not recovered. Business executives have a more steady downward trend. But people in advertising, HMO managers, and nursing home operators show no change or maybe an increase. Around 1980, stockbrokers were rated much higher than people in advertising--now they are about the same.
Then justice and the military:
That's a lot of data, but there's more, so I will save the rest of it for my next post.