The Difference Between The Top Spot And The Second Spot Is Highest In..

Google results, of course.

"A study from Optify [PDF] has revealed 37% of Google users are likely to click on your website link if it ranks at number one in Google search results pages while the CTR dips to 12.5% for sites that rank at position two in Google. The report also says that the average click-through rate for being on page one of Google is 8.9% while it drops to 1.5% for sites that appear on Google’s second page of search results."

Statistics Source: Labnol