According to this article by Education Week reporter Debra Viadero, the "percentages of students failing math in 9th grade" went up after the Chicago school system began requiring algebra in the math curriculum.
While the number of failures went up, there was no concurrent bump in achievement:
By the same token, the researchers say, the change did not seem to lead to
any significant test-score gains for students in math or in sizeable increases
in the percentages of students who went on to take higher-level math courses
later on in high school.
“This policy that Chicago tried in 1997 seems to be sweeping the
country now and not a lot of thought is being given to how it really affects
schools,” Elaine M. Allensworth, the lead researcher on the
study, said in an interview.