Good lord, some of you people are prolific communicators!
The reason I'm curious is because I've just upgraded our family plan to the "unlimited" tier due mainly to my wife's texting, but also my own increases. Before I got my iPhone, my texting was limited to once or twice a month because of the extreme difficulty of texting on an 12-key setup. When we got iPhones, we both opted for the 200/month level just so we wouldn't get charged for the texts our friends were sending us. But then something happened.
We discovered that texting is far superior over voice conversations when you want to talk to other parents with small children. See, when you have kids, the peace and quiet necessary for a phone conversation is in extremely short supply. When most of your friends have kids too, conversations about life and how you're doing and all that become nearly impossible. Not so with texting. I can text over the din of children yelling and/or playing the recorder at high volume. I can resume a text conversation anytime I have a spare 30 seconds. It may take a day or more to have a conversation with a friend, but that's better that the way it used to be, which was rarely talking at all.
I also like the fact that, like an email, texting doesn't necessarily demand an immediate answer. Obviously there are situations where you damn well better answer your SOs text, but outside of that kind of situation, you get back to the text when you can. No pressure to do it RIGHT THIS SECOND!!! like there is with a phone call.
I also long considered it far to informal for work-related communications, but I've been able to retrieve text conversations to "refresh" someone's memory in the same way I use email when someone tries to play dumb about something. It's a handy way to get something in writing, so to speak, with people who don't have ready access to email during the work day. I've since re-evaluated my stance on texting for work. Obviously you don't abbvt evREthng when using it professionally, but ultimately it's just another form of written communication.
Anyway, I'm probably somewhere on the cusp of the 20/day level. Most days it's really minimal, but the averages get pushed up on days where there is a conversation to be had. My median average day would be pretty low, I suspect. But the levels have been steadily growing each month since I got the iPhone...