I am not sure if this is the right observation. However, I have seen most applicants who have filed their application in 2009 getting calls and medicals in 2010.
It means to say, though 4131 was high priority job : there were delays across most embassaies.
It is very difficult to draw a trendline, as the sample we get from the forum is a miniscule of the total percentage of FSW applicants.
Anyways, lets hope Lady Luck shed some luck on our files and it surfaces to the top, from the large pile of files.
-Matlal.