Each free account have 15 GB after signed up. But, you can extend with this free way:
(Note: Clean your browser cache before signup: With Chrome, Firefox, IE press Ctrl+Shift+Del)
Step 1: Connect to https://www.bing.com/rewards/dashboard
Step 2: Use your Microsoft account and login to get 100 GB free. Note that you can use FB+ or G+, T+ to sign in.
This program applied to US only. So, you must use VPN or VPS to change IP to US first.
Expired: 28th February
Here's my account:
If you wanna find the fastest way to have US IP, you can use THIS VPN service