I hardly see my friends

I'm 27 and currently I'm down to about 4 friends give or take who I actually hang out with. My problem is that I feel that I don't see much of them that often. Out of the 4 I have one friend who probably only wants to hang out every 6 months! The others I see a bit more but still only every month or so. I don't usually go out with all of them as they are individual friends and were not a group of friends. At most I'll be seen in a group of 3 when I'm out but usually 2. But anyway on average I probably see my friends about once a month. This can vary a lot but I'd say this was the average. Is that normal for somebody my age?