This is a fascinating file! http://184.108.40.206/surveys/international/intlindicators/pdf/Teachers_working_time.pdf
It gives a comparison of the US and other countries with respect to the number of hours teachers teach. It does not provide statistics of how the students fare in this countries, but it is fairly common knowledge that these countries are (generally) doing better to educate children.
We have, I think, tended to equate hours of teaching with higher student performance. Not to say that students will "automatically" do better the fewer hours (individual) teachers have to teach them, but it does seem in the American system that the so-called accountability is (mis)placed on teachers instead of students.
What teacher at the secondary level hasn't felt exhausted and demoralized at the end of a week, thinking, "I have nothing left!" Our American system seems to resemble more of an assembly line than a school. Undoubtedly, American adminstrators think, "Those lazy Europeans! Those teachers do nothing!" But look at the quality of their "product." Less is more.
Wow, a school that expected more preparation (by giving them the time and breathing space necessary to do it well) and less contact hours per year from teachers. That would be innovative (and so simple).