Internally, we measure activity levels for our well servicing operations primarily through our rig and trucking hours. Generally, as capital by E&P companies increases, demand for our services also rises, resulting in increased rig and trucking services and more hours worked. Conversely, when activity levels decline due to lower spending by E&P companies, we generally provide fewer rig and trucking services, which results in lower hours worked. The following table presents our quarterly rig and trucking hours from 2015 through 2017.
Key's U.S. working days are the number of weekdays during the quarter minus national holidays.
MARKET AND BUSINESS CONDITIONS AND OUTLOOK
Our core businesses depend on our customers’ willingness to make expenditures to produce, develop and explore for oil and natural gas. Industry conditions are influenced by numerous factors, such as oil and natural gas prices, the supply of and demand for oil and natural gas, domestic and worldwide economic conditions, and political instability in oil producing countries and available supply of and demand for the services we provide. Oil and natural gas prices began a rapid and substantial decline in the fourth quarter of 2014. Depressed commodity price conditions persisted and worsened during 2015 and into 2016. As a result, the Baker Hughes U.S. rig count and the AESC well service rig count, along with demand for our products and services declined substantially, and the prices we are able to charge our customers for our products and services also declined substantially. While we sought to anticipate activity declines and reshaped our organizational and cost structure to mitigate the negative impact of these declines, we have continued to experience negative operating results and cash flows from operations. In 2017, oil prices recovered off the lows of 2016 and spurred an increase in the Baker Hughes U.S. rig count and related well completion activity, however, the same magnitude of activity increase did not occur in our principal Rig Services business, as measured by the AESC well service rig count, as oil and gas producers’ production maintenance spending has not recovered to the same extent as new well drilling and completion spending.
During 2017, we saw some continued improvement in demand and pricing for our services, particularly those driven by the completion of oil and natural gas wells, continued uncertainty around the stability of oil prices dampened the pace of improvement in well services activity particularly as it relates to our customer spending for the maintenance of existing oil and gas wells. We believe that a stabilization of oil prices at a price attractive to our customers will be necessary for the demand and associated pricing of our services related to conventional well maintenance work to improve significantly. Additionally, we believe that continued aging of horizontal wells and customers choosing to increase production through accretive regular well maintenance in these horizontal wells will strengthen demand for and increase the price of our services over the next several years. With increased demand for oilfield services broadly, however, the demand for qualified employees will also increase, which may impact our ability to meet the needs of our customers or offset price increases realized due to inflation in labor costs.