[gavinlit]

"So are you implying that educators cannot be trusted not to cheat? That seems pretty strong. Why would they not be honest and let the scores speak for themselves/the program?"
If you tie achievement on external examinations to school/district funding or to numbers of potential students looking at gaining entry to a particular school in the following year you will find cheating. Educators are human too & if it means the survival of your school (and you know/think/expect competing schools to cheat) then ....
Sad but true.
Besides which - examination performance is not generally indicative (in a causal sense) of genuine learning (although genuine learning does usually lead to higher examination performance in most tasks). You'd need to take a look at the examination questions, how they have changed over the years and how the socioeconomic indicators have changed over the years before getting too excited about a shift in results.