Though some ageing of the drug-using population may be expected, overall drug use is likely to continue to be primarily linked to youth.
Yet the openness to moderate use is likely to increase, driven by changes in the science of addiction, like pharmaceutical treatments.
Second, seat belt use is likely to be endogenous to injury severity.
Smartphone use is likely to go up from around 200m now to 500m by 2020.
Lifetime ecstasy use is likely to be partly influenced by genetic factors, but no twin study has determined the heritability.
Although topical microbicides would be a female-controlled method of prevention, their use is likely to be disclosed to partners.
So if living standards in the poorest countries start to rise again, water use is likely to soar.
Their first use is likely to be by the American army, which helped pay for the project.
It is expected that the publication of statistics will resume on 9 July and overall Taser use is likely to have increased again.
Cannabis is a gateway drug: Although cannabis use is likely to precede the use of 'harder' drugs for most people, this doesn't mean that cannabis causes their use.
The first public use is likely to be at "flight clubs", similar to the way people can hire microlights and be taught to fly them.
