Despite the small percentage, the outage is still affecting millions of users. In April, Apple said that its iCloud user population had reached 300 million, so basic math says that these iCloud services may be out of commission for just under 3 million people.
Apple's status page indicates that the outage started Wednesday night at around 9:30 p.m. PDT. However, the iTunes Store outage is relatively new, as it was not seen in a service snapshot taken at about 4:00 a.m. PDT.
Apple's issue report says that users may be unable to use the services mentioned above, as well as being unable to send or download attachments in iMessage.
In terms of the iTunes Store outage, users are unable to make purchases. 16.6 percent of users unable to add to Apple's coffers is a lot: As of June 2013, the iTunes Store had 575 million active user accounts, so the number of affected users would mean more than 95 million were unable to buy anything.