Many estimates have been published regarding the loss from software piracy, but most are from self-serving organizations and the numbers are always over-inflated. First of all, where would that number even come from? Secondly, they are starting with a false assumption: that every stolen copy represents a lost sale and therefore represents quantifiable monetary damage.
You've 3 kinds of consumers: 1) those that never pay, 2) those that pay sometimes, and 3) those who always pay. Groups 1 and 3 can be ignored. Group 1 was never going to give you money anyway, so you can't count them as lost sales. It's only Group 2 that matters, the ones you might sway through effective copy protection and/or very reasonable pricing. Like everyone else, I don't know how big that group is, but it's not 19 out of 20.
The industry has been struggling with this for as long as there has been a software industry. It affects my own business, too, so I've thought about it a fair amount. The only workable strategy for a small software business is to a) make a quality product with frequent updates, b) price it as low as practical or competitively necessary, c) take good care of your paying customers, and d) forget about piracy.