According to the “Annual Study of Suspensions and Expulsions,
2006-2007,”

…the number of out-of-school short-term suspensions (1 to 10 days) given to students increased 2.1% — from an adjusted 2005-06 total of 301,693 to 308,010 in 2006-07. During this time the number of long-term suspensions (11 or more days) increased 2.7% from an adjusted 2005-06 total of 4,559 to 4,682.

As far as expulsions are concerned,

The number of expulsions in the LEAs decreased from 95 in 2005-06 to 81 in 2006-07.

The report can be accessed here.