I'm not sure, it depends who they have surveyed. Mostly everyone I know has at least tried something at one time or another, but I can't imagine my nan's generation having tried that much. Not that I think "our generation invented sex / fun, etc" but that I don't know what drugs would have been available in 1930's England / Scotland / Wales for them to have tried it, and by the 60's my grandparents had their children and wouldn't have been into drugs.
Also, my dad, who was brought up in the counrtryside in the 60s, still is not entirely sure of the difference between canabis and cocaine or crack. In his eyes weed and pills are one and the same not that he is anti-drugs or antyhing, but that he doesn't understand that some drugs are more dangerus than others.