The Center for Education Reform:

Only 25% of 2012 ACT test takers met college readiness benchmarks in all four subjects tested. The ACT is a college-entrance exam that tests high schoolers in English, Reading, Math, and Science. The ACT defines college and career readiness as “the acquisition of the knowledge and skills a student needs
to enroll and succeed in credit-bearing first-year courses at a postsecondary institution (such as a 2- or 4-year college, trade school, or technical school) without the need for remediation.”
Breaking down college readiness by subject yields better numbers. For instance, 67% of students tested met English college readiness benchmarks. However, that means 33% of students taking the ACT have not been sufficiently prepared by their schools for learning at the next level. And that’s just students taking the ACT.