Static variables are for when you want a variable inside a function to keep it's value if the function is called again.
An example of a static variable could be the following.
function addOne(){
static $i = 0;
$i++;
return $i;
}
echo addOne();
echo addOne();
echo addOne();
Which would return
123
Without the static keyword, this would simply return
111
In your question, you mention you have data that won't need to be changed. As the comments in the question state, you should make this a Constant.