The numbers aren't impressive if you open mobile-optimized sites, but this changes when you visit standard desktop sites. The nice thing is that Google's proxy doesn't slow down browsing, so you may not even notice that you're using it. For some reason, this is the only way to enable Safe Browsing, which protects you from phishing and malware and it's enabled by default in the desktop Chrome. Here's a neat URL that helps you test if Safe Browsing works: http://malware.testing.google.test/testing/malware/.
So, what's your savings percentage?