I did a study in the mid 80s for incoming freshmen to the University of New Orleans. Of public school students, 2/3rs of them were remedial in math or English, and a large portion, about half, I think were double remedial. These numbers included two magnet schools that had numbers where most of the students were prepared and did not need the remediation. This was not a complete study of all graduating students, just an analysis of all incoming freshmen from the New Orleans area going to UNO probably for the year 86, and all I did was compile the data for my boss.
But that, and years of teaching adults in the New Orleans area taught me that the state standards were set too low. It wasn't unusual for a student to have graduated with honors, yet needed remediation in college.
My knowledge is out of date, being in the late 80s and early 90s, but I bet things haven't changed that much yet!
But
Holy crow!
Click on PDF then download the Lousiana info.
They are doing better but have a ways to go compared to the rest of the country and the best schools.
http://www.2005summit.org/en_US/interactive/stateProfile_content.html