The numbers can be looked up.

You said: because most shootings have nothing to do with a crime being committed at all

Here are the gun death numbers for 2007 for the entire nation, all ages.
Accidental gunshot deaths 613
Suicide 17,350
Homicide 12,623 (That number has dropped markedly in the last five years.)
Killed by police 351
Killed in self-defense 276 (That number appears be growing somewhat since 2007.)

So most gun deaths, after suicide, are due to criminal use. Murders is very, very rarely a first offense crime. Almost always the murderer has a criminal history.

A person who has determined to take their own life can easily find many other ways to do it so banning guns won't help there.

Taking guns away from the law-abiding will have no effect upon criminals as they don't obey laws anyway.