As of right now there is no way to decrypt your data and the perpetrators are apparently not able to hand out encryption keys even if you pay the ransom due to them not being able to track 'users' as it were and are unable to link keys to specific infection instances.
You will have to restore from backups.
Updated Wiki Gist
You can keep up with the latest developments covering WanaCrypt0r on this wiki gist now. It's being updated as more developments come in. It's currently still just a fraction of what we expect to see.
Well written summary on WannaCrypt0r by Troy Hunt
Index of public servers affected by WCRY (as of yet ~11'200 results) some are just tips on how to google for affected servers
A lot of the spread is due to VPN connected shares and vulnerable servers that bridge networks. Some of the initial attack also proceeded via standard malware delivery vectors (email,etc) but those details are less well researched.
OK, I need to ask, curiosity malware in my brain instructs me to do so: what is exact status of the Windows 7? I do not see patch for it on the list, and on some lists of affected Windows it is absent. Was it simply patched already?