Well, let me first say that most people will lie about this. Just like they lie about how much TV they let their kids watch. It's just human nature. So try to keep that in mind when attempting to get an idea of "normal."
As far as my own love life, I have to say it varies. There will be some months when once a week would be like a second honeymoon for my husband, and there are months that I'm a bit more...libidinous. Some of it has to do with my stress/energy levels, but a lot of it has to do with my husband. Men don't realize that they still have to WORK at this sex thing, even a few years into the marriage when they think it should be a free ride.
One major romance cramper is the complete lack of spontaneity that you have to live with when you have young children. Gone are the days when you could randomly start making out on your living room couch and then rush upstairs while stripping off your clothes. Now sex has to be scheduled during nap times (if you're both home and in the mood) or after the kids are in bed at night(if you have the energy and if the kids actually STAY asleep).
So with all of these things cramping your style, it's no wonder that our sexual peak (which is supposed to happen in our thirties) is really more of a molehill.
Suggestion #1: Try NEW THINGS! Why should sexual experimentation be left to the college students!? Break out of your hum-drum comfort zone and try something different. Now get your mind out of the gutter, I'm not talking about S&M clubs or spouse-swapping. More like trying new positions, new *ahem* toys of the adult persuasion (plenty to choose from on Amazon of all places). Things that might have made you blush as a new bride are the very things that will give you some much needed spice in your sex life. So let down your hair and have some fun! And have your hubby share some ideas with you in this dept, I'm sure he has plenty.
Now before you start feeling all dirty, let me tell you that I am a Christian woman with strong values. I'm not suggesting you do ANYTHING that is immoral or adulterous in any way (HECK no to porno!). All I'm saying is that, within the confines of marriage, there is still PLENTY of room to play without crossing any lines.
Suggestion #2: Sex is like exercise. You feel good once you're doing it, but getting yourself to actually START can be a real challenge. So if an "opportunity" presents itself and you're not really feeling up to it, try giving it a shot anyway. Most of the time, you'll start getting into it and have a good time. If not, then you can always quit and hubby won't really be worse off, will he? Well...maybe. But he'll recover.
As a side note, my libido was through the floor when I was on birth control pills. Anything that messes with your hormones can be messing with your sex-drive as well. Speak with your Gyno about it if you're concerned.
Suggestion #3: Talk to your hubby (using small, simple words that his sex-starved brain can understand). Patiently explain to him that, when it comes to your sex life, he will get out what he puts in. If he wants the results, he needs to make the effort. And no, that doesn't mean copping a feel when the kids aren't looking, or standing naked in front of you while you're laying in bed trying to read and telling you to "come and get it".
It's called romance, gentlemen. Look it up! Sex isn't a meal ticket to be punched and it certainly isn't your God-given right. Make a woman feel beautiful, spend quality time with her. Be PASSIONATE and actually put a little ENERGY into your seduction and you'll be surprised at the results.
Good luck to us all...we certainly need it.