I Am walking with roughly 10 to 15 people each day at present. Some days I see no one and others, like the other night in Astorga I think there may have been about a dozen in the albergue. Falcon's figures above would also include those who were walking other routes I would imagine. I began in St Jean and took the valcarlos route - which I would be pretty certain they would reccomend a Feb pilgrim to do. I can also recommend the Valcarlos albergue to break your journey, delightful place indeed.
I have found enough albergues open, though there wasn't one open in Hornillos, so we hitched a ride to Hontanas. There wasn't one open at Fromista either, but found a hostal at 25€ each, which I consider pretty good. I have also stayed in a couple of hotels, which means I can sleep in when having a rest! I was advised to call ahead and check which ones would be open, but mostly I haven't. The one time I was assured an albergue would be open (Christmas night) it wasn't, but managed to extricate myself from that one and got a lift, in the dark, 2kms up the road to where one was open. You might find some delightful surprises!
I am doing a blog (addressbelow) if your interested. Sing out if there is anything else I can help you with. Janet
http://mywintercamino.blogspot.com.au