U.S. energy companies this week added oil rigs for a seventh week in a row, extending a seven-month drilling recovery as crude prices held near a 17-month high.

Drillers added 12 oil rigs in the week to Dec. 16, bringing the total count to 510, the highest since January, but still below 541 rigs a year ago, energy services firm Baker Hughes Inc said on Friday.

Almost two-thirds of the rigs added since May, or 121, were in the Permian basin, the nation’s biggest shale oil formation located in west Texas and eastern New Mexico, bringing the total there up to 258, the most since April 2015.

The Baker Hughes oil rig count plunged from a record 1,609 in October 2014 to a six-year low of 316 in May as U.S. crude prices collapsed from over $107 a barrel in June 2014 to near $26 in February 2016. (read full article)