Why keep score? Kinda sets you up to be disappointed alot more. My ex used to do this and it drove me crazy. You want to do something with me in a partnership/friendship...say something, don't hint or it and wait for me to ask.
If it feels unbalanced (or is) and is a problem for you. Say something or stop calling, those are kind of your only options

I'm the same way. I tend to call friends and after I finally realize the calls to any particular person go only one way, I stop calling. Simple courtesy, too often ignored in today's I phone world me thinks,

You teach people how to treat you. If you are not feeling like a valued friend, then you must initiate change or just employ radical acceptance of the situation ...i.e. accept that this is how it is and don't expect it to change or be different. Ever. That allows you to manage your expectations and no longer feel disappointed.

If you don't have a heart to heart to tell them that this is bothering you, then they have no reason to attempt to change even if they value the friendship.

One of two things --- A)) either they respond because they feel obligated to respond and wouldn't mind if the friendship faded away ....or B)) they respond because they are happy to hear from you and just doesn't write first because they 1) are very busy, 2) doesn't want to bother you, 3) feels awkward being the one to initiate (shy? depressed?)

How you continue is your choice.

He or she is predominantly self-centered, really only cares about himself or herself.

A friend in need is a friend indeed.

I do that also. I will respond. But then the other person seems to lose interest. So I say OK.
Why do you drop off contact? If it was You dropping off contact, than you should be the one to re initiate.

Honestly, I wouldn't consider them a "friend"

I've had that problem with a few friends. It really depends on how you feel about it and how you feel about them as a friend. If they are worth the effort and you can accept that is how they are, then continue initiating things. I eventually grew tired of it and let the friendships die (and had zero regrets).

Perhaps they view it as alternating , where as you view it as always requiring you to act first and them just responding .