The table describes MU stage applicable to you (EP) as you start participating in the program. If you started in 2012, MU 1 applies for 2012 and 2013, MU 2 for 2014 and 2015 etc…
First year also permits 90 day reporting. So practices starting in 2012 only needed to report 90 days of MU 1 measures in 2012 and full 2013 MU 1 measures. If you want 2013 payment, you would have implemented OpenEMR by Oct 1, 2013, registered before Dec 31, 2013 and would file results by deadline in 2014.
Then there is 2014 exception for ** all providers ** to only 3 month reporting to allow EHR updates related to MU 2. So effectively OpenEMR can hit MU 2 target by Sep 30 release to meet 2014 MU 2 filing requirements ** for those who started in 2011 and 2012 **.
Hopefully that will not be the case as you would take time to upgrade the software on a reasonable update schedule.