how many canidates are voted for each year?

Answer 1

There are about 500,000 elective offices (Federal, state and local) in the USA (I assume that is what you mean). Some are up for election each year, some every 2 years, some 3, some 4, some are longer or even lifetime selections.

So, I'd say that between 100,000 and 200,000 offices are up for selection each year. Some offices have only 1 candidate, some 10 or more. I'd say that from 200,000 to 600,000 people appear on a ballot each year.