Extremely useful statistics. However, users need to know that IRSC codes are not really unique identifiers. The code was created to identify unique digital tracks (recordings). When older analog recordings (there are millions of them) the publisher assigns it an ISRC code, which shows the year of reissue. If the recording is in public domain, anyone can reissue it and assign it a new ISRC code. Even if the recording is still in copyright, the company can assign each new rerelease a new code - all with a different year. So be careful with interpreting statistics based on these codes.