This chart shows when robots might take over all trucking jobs

Self-driving trucks will take over nearly 100% of trucking jobs, according to a new McKinsey report. The only question is when.

In the US, it could be as soon as 2032 or as late as 2066. In China, where human truckers are relatively cheap, it could be a few years later.

source
http://www.mckinsey.com/global-themes/digital-disruption/harnessing-automation-for-a-future-that-works

There are currently more than 20 million heavy and tractor-trailer truck drivers worldwide, with 1.6 million in the US.