Fix old statistics after URL scheme redesign

I redesigned my site URL-scheme and this of course led to new kind of reports, statistics etc.

Example: I had one blogpost, URLed like this:

After URL redesign, URL is like this:

So all the /content/ URLs were changed to /blog/ URLs.

Now I have statistics for the both URLs.

Is there some way to fix old site statistics to match new redesigned URL scheme? How to tell piwik database to change all /content/ URLs to /blog/ URLs ?