10% of one year is 36.5 days, so they still have time to be completely up before they're below one nine if you use a rolling one year window.

They have one nine at the moment (for the year and overall).

If they stay up for another 2 years with absolutely no additional downtime then they'll reach 2 nines of uptime over the entire service life.

I believe they've had other minor outages, but overall, the lifetime of the service seems to have somewhere around 98.4% uptime. That's counting since November of 2006, when I believe the PSN launched alongside the PS3.