For its own reasons that had nothing to do with the WOD.
Did I say it did? The decline in alcohol use without preceding anti-alcohol measures suggests that the decline in drugs may have had nothing to do with anti-drug measures.
"The creation of grass roots associations such as Mothers Against Drunk Driving, severe penalties against drunk driving, public outcry against fetal alcohol syndrome, decreases in legal blood alcohol concentration limit for impaired driving, 21 year old alcohol purchase laws, abstinence education in schools and colleges, tavern owners being liable for alcohol related incidence, and warning labels on alcoholic beverages are all part of the current movement."
You missed this part: "Most anti-alcohol counter measures have appeared within 20 years after the peak in per capita alcohol consumption during a period of decreasing consumption(Engs 1992b; Linder and Martin 1987). [...] It is interesting to note that most of the anti-alcohol legislation came after the beginning of this decreased consumption [circa 1980]."
Not to me, it doesn't. Apples and oranges.
I wonder if the consumption of milk fell during this period. Pepsi?