Question: The brother pair on the 2018 list of The World 's Billionaires each own how much of Koch Industries ?

text: The World's Billionaires
Annual rankings -- 2018
In the 32nd annual Forbes list of the world 's billionaires , the aggregate wealth of the top 20 richest people on Earth amounted to about 13 percent of all billionaires ' fortunes combined . [ 5 ] A record of 2,208 billionaires were in the ranking and the total wealth was $ 9.1 trillion , up 18% since 2017 . For the first time , Jeff Bezos was listed as the top billionaire due to Amazon 's rising stock price that resulted in one person 's biggest one-year gain in wealth ( $ 35 billion ) since Forbes started tracking in 1987 . [ 5 ] The U.S. had the most billionaires in the world , with 585 , while China was catching up with 476 when including Hong Kong , Macau and Taiwan ; it had 372 when excluding those three places . [ 5 ] Forbes excluded Al-Walid bin Talal and all other Saudi billionaires due to the absence of accurate wealth estimations as a result of the 2017–19 Saudi Arabian purge . [ 16 ]
The World's Billionaires is an annual ranking by documented net worth of the wealthiest billionaires in the world, compiled and published in March annually by the American business magazine Forbes. The list was first published in March 1987. The total net worth of each individual on the list is estimated and is cited in United States dollars, based on their documented assets and accounting for debt. Royalty and dictators whose wealth comes from their positions are excluded from these lists. This ranking is an index of the wealthiest documented individuals, excluding and ranking against those with wealth that is not able to be completely ascertained. In 2018, there was a record of 2,208 people on the list, that included 259 newcomers mostly from China and the U.S.; there were 63 people under 40 and it had a record number of 256 women. The average net worth of the list came in at US$4.1 billion, up US$350 million from 2017. Added together, the total net worth for 2018's billionaires was US$9.1 trillion, up from US$7.67 trillion in 2017. As of 2018[update], Microsoft founder Bill Gates had topped the list 18 of the past 24 years, while Amazon founder Jeff Bezos is ranked at the top for the first time and he became the first centibillionaire included in the ranking. In 2017, Mark Zuckerberg was the only person in the top 10 billionaires list who is under the age of 50, and the only one in the top 20 billionaires list who is under the age of 40. In 2017, 500 of the richest people in the world became richer by $1 trillion, according to a report by Bloomberg News. According to a 2017 Oxfam report, the top eight billionaires own as much combined wealth as the poorest half of the human race.
No Name Net worth ( USD ) Age Nationality Source ( s ) of wealth
1 Jeff Bezos $ 112 billion 54 United States Amazon
2 Bill Gates $ 90 billion 62 United States Microsoft
3 Warren Buffett $ 84 billion 87 United States Berkshire Hathaway
4 Bernard Arnault $ 72 billion 69 France LVMH
5 Mark Zuckerberg $ 71 billion 33 United States Facebook
6 Amancio Ortega $ 70 billion 81 Spain Inditex , Zara
7 Carlos Slim $ 67.1 billion 78 Mexico América Móvil , Grupo Carso
8 Charles Koch $ 60 billion 82 United States Koch Industries
8 David Koch $ 60 billion 77 United States Koch Industries
10 Larry Ellison $ 58.5 billion 73 United States Oracle Corporation