WASHINGTON -- China's Tianhe-2 supercomputer has retained its position as the world's most powerful system for the sixth consecutive time, according to a biannual Top500 list of supercomputers released Monday.

Tianhe-2, or Milky Way­2, with a performance of 33.86 petaflops per second (Pflop/s), was developed by China's National University of Defense Technology and deployed at the National Supercomputer Center in Guangzhou. It has held the title since June 2013.

The Chinese system is almost twice as fast as the next on the list, Titan of the US Department of Energy, which has a performance of 17.59 Pflop/s.

In fact, there has been no change among the ranking of the world's top5 supercomputers since June 2013 in the latest edition of the closely watched list.

"The top five computers are very powerful and expensive," Jack Dongarra, professor of the University of Tennessee and editor of the report, said in an email. "It will take perhaps another year before a new system enters the top five."

Among the significant changes to this list from July 2015's list is the sharp decline in the number of systems in the United States, now at 201.

"This is down from 231 in July and is the lowest number of systems installed in the US since the list was started in 1993," the statement said.

In contrast, China made "a great leap" to 109 systems.

"China received a big boost from Sugon, Lenovo and Inspur," said Dongarra. "The large number of submissions came from Sugon."

According to the Top500 statement, Sugon has overtaken IBM in the system category with 49 systems, while Lenovo, which acquired IBM's x86 server business last year, has 25 systems in the list, up from just three systems on the July 2015 list.

In addition, some systems that were previously listed as IBM are now labeled as both IBM/Lenovo and Lenovo/IBM.

Inspur, the third vendor from China, now has 15 systems on the list.

"China is ... carving out a bigger share as a manufacturer of high performance computers with multiple Chinese manufacturers becoming more active in this field," the statement concluded.

Overall, HP leads the list with 156 systems followed by Cray with 69 systems and China's Sugon with 49 systems. IBM ranks fourth with 45 systems. Lenovo ranked sixth while Inspur ranked eighth on the list.

The Top500 list is considered one of the most authoritative rankings of the world's supercomputers. It is compiled on the basis of the machines' performance on the Linpack benchmark by experts from the United States and Germany.