Larry Kim is the founder of WordStream and CEO of MobileMonkey
"Conventional wisdom says that a good conversion rate is somewhere around 2% to 5%. If you're sitting at 2%, an improvement to 4% seems like a massive jump. You doubled your conversion rate! Well, congratulations, but you're still stuck in the average performance bucket...If you're currently getting 5% conversion rates, you're outperforming 75% of advertisers … but you still have a ton of room to grow!"