Where did you get the numbers for how many hours a teacher works in a school year? Because from everything I looked at this infograph is incorrect. Perhaps you meant the amount of time teachers spend teaching vs other duties, then it looks like it would be correct. OECD (2011), Education at a Glance 2011, Table D4.1, available at http://dx.doi.org/10.1787/888932465398.
From what the OECD paper shows, teaching hours may not have a significant influence on how well students preform on test scores. Perhaps we need to lower the amount of time teachers teach?
I also believe this infographic needs to tease out the differences between lower level and higher level schooling to be remotely accurate given the source.