“They” in this sentence denotes Americans collectively, not just Americans who drink. Although yes, in actual fact outside the world of grammar, it’s only the alcohol-drinking Americans who are consuming more alcohol, the sentence doesn’t break “Americans” into subgroups in the way that your sentence implies.
You mean “they still do”? Because obviously they, we, still are… minus those that died since and plus those that were born.
Right or wrong, I believe the intended message was, “[They] began drinking more. They still are (drinking more).”
“They” in this sentence denotes Americans collectively, not just Americans who drink. Although yes, in actual fact outside the world of grammar, it’s only the alcohol-drinking Americans who are consuming more alcohol, the sentence doesn’t break “Americans” into subgroups in the way that your sentence implies.