The article states the obvious. 99% of drugs seized at the Mexican border came from Mexico.
Is a stupid article and “study”. Of course vast majority of drugs from other countries come in via Mexico.
Question should be how much of Drugs used in U.S. are made in the U.S. vs. coming from outside the country?
You may want to read slower because the article says “seized at U.S. borders has come from Mexico”
Seems to imply all borders, not as you stated seized at “mexican” border.