So Many More Ram Lambs Than Ewe Lambs

What are the odds that out of 11 lambs only 2 would be ewes?

I have had 6 lambs born so far and only 1 was a ewe.  Somebody who bought 2 ewes from me has also had lambs born, out of the 5 lambs they had only 1 was a ewe.

It is the sperm from the father that determines what gender the young are going to be so I am wondering if the early breeding somehow predisposed things so that we would get more ram lambs born than ewes.  These sheep would have been bred in the middle of the summer in order to have lambs now, so I am not sure if that somehow affected the odds and caused us to have so many more males?

 I am wondering if there are any other people out there who have noted that the time of year when they breed their sheep seems to have any bearing on what gender the young are more likely to be.  Usually its a bit more of an even ratio.

Getting a high percentage of ram lambs would be great if I were strictly breeding for the meat market, because most of the buyers in my area want ram lambs for meat, but I am a sucker and prefer to sell my sheep as pets, so I prefer to get ewe lambs.