FILE - In this Nov. 20, 2018, file photo an American flag flies outside New York Stock Exchange. Stocks are opening solidly higher on Wall Street as the market claims back some of the ground it lost in steep drops over the previous two days. Technology and industrial stocks were among the biggest winners in early trading Tuesday, Dec. 18. (AP Photo/Mary Altaffer, File)

A currency trader walks by the screen showing the Korea Composite Stock Price Index (KOSPI) at the foreign exchange dealing room in Seoul, South Korea, Tuesday, Dec. 18, 2018. Asian stocks fell on Tuesday, tracking losses on Wall Street as traders braced for an interest rate hike by Federal Reserve. (AP Photo/Lee Jin-man)

A currency trader walks by the screen showing the Korea Composite Stock Price Index (KOSPI) at the foreign exchange dealing room in Seoul, South Korea, Tuesday, Dec. 18, 2018. Asian stocks fell on Tuesday, tracking losses on Wall Street as traders braced for an interest rate hike by Federal Reserve. (AP Photo/Lee Jin-man)

Heads of the delegations react at the end of the final session of the COP24 summit on climate change in Katowice, Poland, Saturday, Dec. 15, 2018.(AP Photo/Czarek Sokolowski)

FILE - In this photo provided by the Interior Department shows Interior Secretary Ryan Zinke arriving for his first day of work at the Interior Department in Washington, Thursday, March 2, 2017, aboard Tonto, an 17-year-old Irish sport horse. Zinke will be leaving the administration at year's end, Trump said Saturday, Dec. 15, 2018. (Interior Department via AP)

FILE - In this Dec. 30, 2016 file photo, a tanker truck waits at the storage and dispatch terminal of Petroleos Mexicanos (Pemex), Mexico's state-owned oil company, in the port of Veracruz, Mexico. Mexico plans to boost crude production at state oil company Pemex by 45% over the next six years as the country invests more heavily to stem declines in output and revenue. President Andres Manuel Lopez Obrador said Saturday, Dec. 15, 2018. the goal is for Pemex to produce 2.40 million barrels a day of crude, up from 1.65 million currently (AP Photo/Felix Marquez)

Smoke billows from a chimney of the Solvay factory for production and processing of plastic materials, in Ospiate, near Milan, Italy, Friday, Dec. 14, 2018. The climate change conference, COP24, is closing today in Katowice, Poland. (AP Photo/Luca Bruno)

FILE - In this Sept. 9, 2010, file photo, a massive fire following a pipeline explosion roars through a mostly residential neighborhood in San Bruno, Calif. The California Public Utilities Commission said Friday, Dec. 14, 2018, that an investigation by its staff found Pacific Gas & Electric Co. lacked enough employees to fulfill requests to find and mark natural gas pipelines. A U.S. judge fined the utility $3 million after it was convicted of six felony charges for failing to properly maintain a natural gas pipeline that exploded south of San Francisco in 2010, killing eight people. (AP Photo/Jeff Chiu, File)

FILE- In this Nov. 29, 2018, file photo trader Timothy Nick works on the floor of the New York Stock Exchange. The U.S. stock market opens at 9:30 a.m. EST on Friday, Dec. 14. (AP Photo/Richard Drew, File)