CO 737-500 w/ winglets


At DAB this morning I saw a CO 737-500 with winglets, I was wondering when did they decide to put winglets on the 737-500. Also how many other aircraft have them or are going to get them.

I saw N16617



Werkur caught a nice picture of another -500 with winglets, posted on page 13 of THIS THREAD. Near the top of the page. That one was N16650.