League-wide, teams were required to spend 99% of the cap in 2011 and 2012. In 2013 and beyond, they must spend 95% of the cap. In the event that player costs are less than this overall league minimum, then, on or before April 15 of the next League Year, the NFL must pay an amount equal to such deficiency directly to the players.
In terms of minimum salary for each team, the salary floor is 89% of the cap. That became effective in 2013, as this requirement was by-passed in 2011 and 2012. Hence, there was in essence no salary floor in 2011 or 2012.