1. A proportion stated in terms of one-hundredths that is calculated by multiplying a fraction by 100: If all of the apples were picked, if would be 100%, whereas if only half of the amount of apples were picked, it would be 50%, and if none of the apples were picked, 0% of the apples were picked.
2. A proportion or share in relation to a whole; a part: The hecklers constituted only a small percentage of the audience."
3. An amount, such as an allowance, duty, or commission, that varies in proportion to a larger sum, for example, total sales: They are working for a percentage of the gross sales.

When preceded by "the", percentage takes a singular verb:

The percentage of unskilled workers is relatively small.

The percentage of errors in his term paper is excessive.

When preceded by "a", percentage takes either a singular or plural verb, depending on the number of the noun in the prepositional phrase that follows:

A small percentage of the new workers are unskilled.

A large percentage of the crop was lost because of the lack of rain.

A large percentage of the electorate still remains undecided.