I would imagine that the marijauna related emergency room visits were from people that had accidents while stoned. Just a guess though.
As for number versus number stats there are roughly 250 million people in the us that use caffeine or related products more than once a week.
0.796 visits per 100,000 users a year for caffeine
13.3 visits per 100,000 users of steroids (remember these are almost all related to infections)
9.64 visits per 100,000 users of alcohol
1.91 visits per 100,000 users of tylonol
25.001 visits per 100,000 users of cocaine
89.9 users per 100,000 die from smoking each year
smoking is more deadly than cocaine use,,, this is a scarey stat