What is a typical ratio of the number of reviews to the number of sales? I realize that any answers will probably be "anecdotal" as opposed to "statistically valid" but I'm curious. What I'm really wondering is, how many books do I need to sell before I can expect to see a review? Everyone says that reviews help sales, and I certainly wouldn't mind something helping my sales. Do I need to sell 100, 500, 1000, more? before I can reasonably expect to see a review. A nice one would be good, but anything to indicate somebody actually read it would be a plus.