Is that 600 homicide convictions?
The police or a prosecutor may file a homicide charge in the case but the prosecutor, judge, or grand jury may later rule it as self defense.
That's often the problem with crime statistics. It's based on reporting. A bad neighborhood may have a surprisingly low crime rate if no one calls the cops anymore.
I would still ask the question why some regions have a legal requirement for individuals to run away from danger? Self defense is a basic human right. Protecting yourself is important, but placing your back to danger is not always the safest choice. People can cite "increases" all they want, but if removing myself from the situation actually places myself or loved ones at greater risk then I'd prefer to have the law on my side should I choose to defend myself.