How would you define a super delegate?

Why are there so many super delegates in the nomination process for the President of the United States?

Why are there so many super delegates?

Given the table you have published, I assume that you are specifically asking about the Democrats. (Note that Republicans have a similar system, but not the term pledged delegate use instead of super delegate. Both parties set up approximately 25% of the delegates as this super / non-mortgaged status.)

The reason the DNC has so many super delegates is because that's how they set up. Wikipedia gives a good summary of the story.

The Hunting Commission recommended and the Democratic National Committee passed a rule that provided some delegate seats for Democratic members of the Congress, as well as for party leaders and vice-chairs. Under the original hunt plan, 30% of all delegates were super delegates, but when it was finally implemented for the 1984 elections it was 14%. The number has increased steadily and is now around 20%.

TO UPDATE:

To answer your other assumption in your comments:

I thought super delegates weren't mortgaged by definition

No - at least not in terms of DNC terminology. A super delegate simply means that he is a delegate directly elected by the Democratic Party. When and whether they commit or not is up to each individual. The diagram in your answer only shows the super delegates who are so far have committed. (As well as the regular delegates selected for each candidate so far).

As mentioned earlier, in GOP terminology, you can think of a super delegate as a non-pledged delegate.

Clear as mud? :) :)

user4012

TL; DR: Because the establishment needed a nuclear option to prevent too far-removed mainstream candidates from winning the nomination and losing the general election.

Tlehman

Understand, this is there to prevent another McGovern situation.