This Trend In Texas Is Very Disturbing

The charts above, from the Dallas Morning News, shows a very disturbing trend that is happening in the state of Texas. Over the last decade, the number of arrests have decreased -- but over that same time period, the number of deaths of people arrested have increased.
Normally, if the number of arrests went down, one could expect the number of deaths to also go down. It's a viable question to ask why is this happening? Are the police becoming more violent?