I wouldn't say that the figure of Facebook friends is an indication of number of people I really cared. I do care some of them (sometimes sending wishes for them), but a majority of them are either my classmate in high school, a junior in university, a (former) co-worker, or someone whom I met in social gathering that shared common interests and wanted to hear/talk with them. It's like the use of Facebook as a directory since everyone has one.

Conversely, there are plenty of friends whom I know personally, but did not connect via Facebook (we use IM for that). This may probably be counted towards the close friends I really cared for; only few (no more than 10) people fits this criteria of mine.