This is the picture I took of the early results of a little poll we made up over coffee.  You will notice that there seems to be a nice balance of staying and leaving, but then...all those people looking; looking for something better, more rewarding.

Job boards make that so easy now.  There are boards for everyone's skill set, all over the world.

And then--back to the poll-- there's that grumpy middle: disengaged, spends their time surfing the net, or generally spreading good cheer.  Not.

What do you need to do? 
Suggest:  Identify the people on the floor that you can't lose.  Find out how things are going with them.

• Do yourself a favour.  Take the morning, and do a compensation search on your staff roster.  Then take a look at what you are actually paying them.  Find out what the underpaid are actually up to (if there's a reason why they aren't being compensated at least average). 
• Please note that not everything is about the money.
• There are lots of things going on with people: family, health, pressures of debt or other difficulty.

Things are winding-up through the 'festive' season.  These can be the most stressful times of the year.  Better to consider a plan, then implement in January.

I was sent a book called the Deadly Sins of Retention, by Murphy and Burgio-Murphy.  Take a look.  It's a quick read; a user's guide really. 
This takes you to Amazon.com: The Deadly Sins of Employee Retention.