Print dollars for Web dimes — or so the math goes when media executives talk about the growing migration of their customers’ advertising budgets from print properties to the Internet. When those ad rates will start to even out is anyone’s guess (don’t hold your breath). Meantime, newspapers are enjoying strong growth in local online advertising — about $3.1 billion — but are losing share to pure-play Web sites, according to a new survey of local Web site revenues by Borrell Associates.