The trend suggests the violence was led by opportunist raiders, despite a report last week claiming it was sparked by anger at cops.

There was a spike in 2007 and 2008, but the long-term trend suggests those were the outlier years rather than now.

This trend suggests the eventual emergence of a marked social hierarchy.

Their persistent southeasterly trend suggests deposition of the loess by prevailing northwesterly winds, possibly anticyclonic winds blowing from the retreating ice sheet.

The present trend suggests an increased use of air-filled membranes because they can be deflated or inflated more rapidly, and they are little affected by freezing conditions.