That's a good question.... my lil one is 8 months and still varies, sometimes she sleeps through and more often than not, she wakes up about 3 times a night. :/
Do you breastfeed? They wake up more often if you are breastfeeding. My son didn't start sleeping through the night until 8 months or so and it's more because he was on formula so it kept him full longer.
He's almost a year and has come back to waking at night- not to feed though. Just to be comforted. I think he's teething more.