Once per year online surveys are the lazy clubs way of check-boxing 'we listen'.
If this is the primary way you gauge the pulse of your club, you are probably getting a false positive.
At my day job, we 'survey' our customers online and get some information, but the in-depth survey we do in person is where we find the truth.
Anything below an '8' means trouble. The traditional 'satisfied, somewhat satisfied, neutral', etc., is helpful, but for some reason numerical grades always tell more of the story - in person.
A quick '9 or 10' is great, but what about the hesitant '7'? Is it really a '7'? Voice inflection and body language says it's not, but you can't pick that up over the internet. This is why you need to survey as many members as you can in person. Again, at my day job, we conduct these monthly with a sub-set of customers. After 12 months, we have asked everyone, both online and in person. Do this and member retention will no longer be a mystery.