The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.By Madeline Schnapp of TrimTabs Investment Research NEW YORK ( TheStreet) -- Based on our analysis of real-time income tax withholdings, we estimate that the U.S. economy added 171,000 jobs in June, up from 127,000 jobs in May. Employment has increased for nine consecutive months, although job growth in that period averaged only 154,000 jobs per month. We attribute the acceleration in employment growth in June to lower crude oil prices. Unfortunately, oil prices rose 3% in the past two weeks, which could slow job growth again. For the economy to gain traction, oil prices need to come down and stay down. If oil prices remain elevated, the economy's apparent improvement in June could be short-lived.