DKII on 17 June 2008
Ok here's the data available:
Dr Mario:
Time Spent Playing/Times Played
Total: 64,681 Hr / 49,512 Times
Per person: 4 Hr 56 Min / 3.78 Times
Divide either total number by the per person number to get what this article is calling "registered sales". So it looks like it's just the number of people who sent data to Nintendo for these stats.
Not that we can't possibly extract something from that. ;)
