Blueberry muffins

When your children wake you up at ungodly hours, sometimes there is just one thing to do, and that is bake blueberry muffins.  Actually, because my kids got up at ungodly hours, I am up and showered and motivated to take Ciera to playgroup, and figured, why not take blueberry muffins to playgroup.  They may or may not go well, they aren't an overly sweet muffin.  Most of the moms who show up to this playgroup tend to be on a health kick, so I figured a less sweet muffin would be good, plus I used greek yogurt instead of milk (I didn't have milk, haha).  I topped it with a lemon streusel top.  I also made 48.  I was trying to make the recipe make 24, but I guess my math was way off.  This is why I am failing at math.  Oh well, hope everyone enjoys these.