Crashes caused by rear ending - where a vehicle crashes into another one in front of it - have risen and now account for a third of all crashes in NSW and nationally, says an analysis of insurance claims showing increased driver distraction.

The latest annual crash index by insurer AAMI also found more than a quarter of NSW accidents were caused by drivers failing to give way.

Nose to tail accidents account for a third of all accidents. Credit:Robert Peet

About 23 per cent of crashes across the country were caused by failure to give way, compared with 26 per cent in NSW.

For the third year in a row, AAMI's crash index found rear ending accounted for a third of all claims, rising from 30.84 per cent in the year ending June 30, 2017, to 32 per cent in the year to June 30, 2018.