Right, I had not thought about this aspect of things, both the 500mg and 1g tubes I have at home contain a total of only 8g.
It doesn't seem difficult to accumulate more than 8g at home over time though, I'm not a big consumer of these and I have 12g at home, in three tubes. I remember my grand parents having a lot more packs at their place.
In a lot of Europe (certainly UK, I heard also France), you can only buy 16 pills (about 8g) at a time, unless your doctor writes you a ticket.
The pills themselves may contain a lot of chemical, but the whole pack doesn't contain enough grams for a successful impulsive suicide. You would need to go to a second drug store, by which time you'd probably decide not to do it. Hence the reduction in death rate.
The problem of liver damage due to chronic over use continues .