setting session.gc_probability

OK, we're having an argument in our shop. This is what the manual says about garbage collection: "session.gc_probability specifies the probability that the gc (garbage collection) routine is started on each request in percent. Defaults to 1." Somebody here says that a value of "1" means 100%, i.e., that this value is really a proportion and not a percent; a value of "1" means garbage collection is launched on every page request. I say that a value of "1" means garbage collection is launched on 1 out of every 100 page requests, i.e., it truly is a percent. Can anybody confirm the correct interpretation? TIA Kirk