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Any comments from other content sites?
USA->California->LA->Venice Beach->Places to eat ... etc etc
I should have mentioned something about structure in the lead post - no doubt makes it difficult to generalise
If your site is poorly structured or your pages have a hideous breadcrumb trail then 16 might mean you have visitors who found it difficult to find their way around but who perservered anyway....
But it might be that 16 is a genuine figure.
All data needs to be taken with some salt.