Skyscrapers are inundating city skylines in 2015 with China leading the boom.

Looking specifically at skyscrapers over 200 metres, data from the Council on Tall Buildings and Urban Habitat (CTBUH) reports that there are currently 626 skyscrapers under construction across the globe. A whopping 349 of these buildings will be housed in China alone.

A total of 163 are set to be finished this year, with 116 will rising in China.

China is also preparing to take second place on the world’s tallest skyscraper list with the almost completed 632-metre Shanghai Tower set to overtake the 601-metre Makkah Royal Clock Tower Hotel.

The rapid rise of skyscrapers in China has some analysts worried as traditionally high skyscraper activity has been linked to economic collapse. However, the country’s buildings are at least partially state-financed, according to the CTBUH.

Supertall buildings are also often criticised for boasting “vanity height” and having ego-centric developers behind them.

In 2013, the managing partner of Archgroup Consultants, which led the design of the 355-metre JW Marriott Marquis hotel tower in Dubai told The National that “Tall buildings are a reflection of the ego. The second benefit is the selling prices they command and the panoramic views that they offer.”

In China’s case, last year, CTBUH executive director Anthony Wood told Bloomberg that “What’s happening in China is similar to what happened in the US 80 to 100 years ago, on a different scale.”

“Cities are competing both within China and also globally for attention and for the appearance that they are first-world.”

Another view was found in the recent study Skyscraper Height and the Business Cycle: Separating Myth from Reality which states that “the decision about how to build tall has been based on economic, marketing, emotional and strategic considerations.”

The researchers use One World Trade Centre as an “emotional and strategic” example, noting that the building rose 1,776 feet to be the tallest in the US and also also reflect the year of American Independence.

“While we don’t deny that psychological and ego-based motives are present in the skyscraper market, they do not appear to be a systematic part of it,” the study’s authors stated. “The fact that heights rise over the business cycle indicates that height is a rational response, on average, to rising incomes.”

In many cities, skyscrapers are also an indication of economic strength. The rise of residential and mixed-use skyscrapers also aligns with global reports of a need to house population rise and urbanisation.

In terms of the actual height, the 600-metre mark looks to be the sweet spot for skyscraper height across the globe. China is also predicted to hold the title of six of the 10 tallest skyscrapers in the world by 2020.

Here is what the current skyscraper market looks like as of June 2015:

Top 10 Tallest Buildings (Completed)

1. Burj Khalifa, Dubai, 828 metres
2. Makkah Royal Clock Tower Hotel, Mecca 601 metres
3. One World Trade Centre, New York City, 541.3 metres
4. TAIPEI 101, Taipei, 508 metres
5. Shanghai World Financial Centre, Shanghai 492 metres
6. International Commerce Centre, Hong Kong, 484 metres
7. Petronas Tower 1, Kuala Lumpur, 451.9 metres
8. Petronas Tower 2, Kuala Lumpur, 451.9 metres
9. Zifeng Tower, Nanjing, 450 metres
10. Willis Tower, Chicago, 442.1 metres

An interesting observation is that only the Burj Khalifa houses a residential component with the remaining nine buildings either for office purposes or mixed-use office/hotel skyscrapers.

Top 10 Buildings Over 200 Metres (Under Construction)

1. Kingdom Tower, Jeddah, 1,000 metres
2. Suzhou Zhongnan Centre, Suzhou, 729 metres
3. Ping An Finance Centre, Shenzhen, 660 metres
4. Wuhan Greenland Centre, Wuhan, 636 metres
5. Shanghai Tower, Shanghai, 632 metres
6. KL118 Tower, Kuala Lumpur 610 metres
7. Goldin Finance 117 , Tianjin, 117 metres
8. Pearl of the North, Shenyang, 568 metres
9. Lotte World Tower, Seoul, 554.5 metres
10. Nordstrom Tower, New York City, 541 metres

In contrast, over half of these skyscrapers house a residential component. Six are located in China.

Top 10 Buildings Over 200 Metres (Proposed)

1. Burj 2020, Dubai, 660 metres
2. Signature Tower, Jakarta, 638 metres
3. Rama IX Super Tower, Bangkok, 615 metres
4. Lanco Hills Signature Tower, Hyderabad, 604 metres
5. Kingkey Jingdou, Shenzhen, 600 metres
6. Rose Rock International Finance Centre, Tianjin, 588 metres
7. Landmark Tower, Hong Kong, 580 metres
8. Hyundai Global Business Centre, Seoul, 571 metres
9. Baoneng Binh Centre Tower 1, Hefei, 550 metres
10. Zhongtian Tower, Guiyang, 550 metres

Each of these demonstrates that 600-metre sweet spot, and again, six are housed in China.

Finally, a brief look at the five tallest towers set to be completed by year end:

1. Shanghai Tower, Shanghai, 632 metres
2. Marina 101, Dubai, 436.5 metres
3. 432 Park Avenue, New York City, 425.5 metres
4. Capital Market Authority Tower, Riyadh, 385 metres
5. Eton Place Dalian Tower 1, Dalian, 383.1 metres

As structures soar sky high, so do costs according to Emporis, an international provider of building data. Emporis released a report of the The World’s 10 Most Expensive Skyscrapers last December.

The Burj Khalifa, the world’s largest building, surprisingly came in at fifth place at $1.5 billion with One World Trade Centre the most expensive building ever built at $3.9 billion. London’s The Shard came in at $1.9 billion – four times its original budget according to ArchDaily.

“The reasons for the immense costs of skyscrapers are varied in nature,” Emporis said. “With some buildings, it is known even at the planning stage that they will be cost-intensive, for instance in order to meet the latest environmental standards. Other projects, by contrast, become increasingly costly during construction itself due to unforeseen events or delays.”