Letters of recommendation

For some unknown reason I have a huge number of students coming to ask me to write letters of recommendation. So far this semester it has been about 30. In contrast my colleague in the office next door has had none. I don't understand this. Why are so many students, many of whom only took one class from me, asking me to write them reference letters? It might make sense if they had all earned straight As from me. But, this is not the case either, only some of them fall into this category. Others do not. One student took one class from me and only earned a C+, but still wanted me to write a letter. Some others are in the B to B+ range. Does anybody have any explanation for why I have so many reference requests and my British colleague next door has none? Is it a gender thing? Do students prefer to have letters written by men?