Refinery giant Tüpraş continued its longtime leadership as Turkey’s biggest industrial enterprise, according to the "Top 500 Industrial Enterprises of Turkey 2019" survey announced Monday.

According to the survey, which dates back to 1968 and is prepared by the Istanbul Chamber of Industry (ISO), Tüpraş again topped the list with a production-based sales value of nearly TL 87.95 billion ($14.48 billion).

Established in 1983, Tüpraş has been leading the list for years.

Automaker Ford also maintained its second position with a production-based sales value of around TL 37.07 billion. Toyota Automotive again ranked third with TL 25.85 billion.

They were followed by another carmaker, Oyak Renault, with TL 24.63 billion, while STAR Refinery, a subsidiary of Azerbaijani integrated drilling and well services management corporation SOCAR, joined the list for the first time and ranked fifth with a production-based sales value of TL 20.83 billion.

The survey revealed that the country’s top 500 industrial enterprises managed to increase their production-based sales by 16.4% in 2019 to over TL 1 trillion, up from around TL 878 billion in 2018.

Last year, one U.S. dollar traded for TL 5.68 on average, compared to 4.82 in 2018.

The percentage rise last year was the lowest of the last three years compared to 33.2% in 2017, and 34.5% in 2018.

ISO 500 companies' exports increased by 2.4% in the year to $73.5 billion, making up 42% of Turkey’s total industrial exports, while the number of companies exporting increasing to 463 in 2019, compared to 409 30 years ago.

Speaking of the survey, ISO Chairman Erdal Bahçıvan listed factors such as a drop in domestic demand, a decline in inflation, contraction in global trade and a downward trend in commodity prices as having an effect on a slowdown in ISO 500’s growth performance.

However, he pointed to two positive developments that he said were promising for the future.

"Since the last three years, the share of medium-high and high-tech industries in the created added-value has been increasing steadily. For the first time in 2019, the share of medium-high and high-tech in the created added-value has surpassed 30% and reached 30.4%. The increase is thought to be mainly due to the defense and aerospace industry sectors, which have seen a major breakthrough in recent years," he said.

Bahçıvan also stated that research and development (R&D) expenditures of the top 500 firms increased by 152% in 2019 to reach TL 9.7 billion.