Suicide can have a lot to do with easy availability of the means.

When they changed the type of gas avaiable on the mains in Britain, to use North Seaas instead of Coal Gas, one side effect was that it wasn't poisonous any more. Rather to the surprise of everyone the suicide rate from all causes plummeted - between 1963 and 1975 ity went down by 40 per cent.

Sure there are always other ways of killing yourself - buy for a lot of people the fact that they couldn't end it all by sticking their head in the gas oven was enough to stop them taking their life.