An average of 9.3 million people per day log onto file-sharing networks worldwide. That's up from 7 million in 2004 according to research firm Big Champagne. Approximately a billions songs are traded online every month.
At the same time music sales have fallen 17% from a peak in 2000 of $12.7 billion.
There is probably a correlation, but even if you could (and the RIAA may have found a way); what purpose is served by suing 9.3 million people?