Indeed the rich get richer. Or at least most of them do.

The 25th edition of the Forbes list of the world's billionaires is larger (1,210) and richer (a combined wealth of $4.5 trillion) than ever before. Yet only one of every three billionaires is an American; a decade ago one out of every two billionaires on the list called the the USA home. Only six percent of the Americans on the current list are new, compared to 47 percent of Chinese and 30 percent of Russians.

Four of the new American billionaires are heirs of Dan Duncan, who was the richest Houstonian on the Forbes list last year. Duncan died unexpectedly last March.

Other than the Duncan siblings, the list of the richest Houstonians on the planet is the same as last year, although some have moved markedly up — and down — on the list.

According to Forbes, Rich Kinder is the richest Houstonian, with a net worth of $7.4 billion. Referred to as the "pipeline prince" by the magazine, Kinder is No. 128 on the list of world billionaires (39th in the U.S.). His net worth has doubled over the past year in large part to a public offering of the company he founded, Kinder Morgan, that raked in nearly $3 billion. Last year, Kinder was No. 249 on the list.

John Arnold, the 37-year-old head of hedge fund Centaurus Advisors, is No. 336 with $3.3 billion. Last year, he was No. 212 on the list. Forbes estimates his net worth has dropped eight percent in the past year. Arnold and his wife have pledged half of their wealth to the Gates-Buffet Giving Pledge.

Scott Duncan, the city's youngest billionaire at 28, and his three sisters, Randa Williams, Dannine Avara and Milane Franz tied at No. 362, with $3.1 billion each. They each assumed control of part of their father's $12.4 billion pipeline empire.

Other oil or energy related billionaires include George Mitchell (No. 420, with $2.7 billion), Jeff Hildebrand (No. 651, $1.9 billion), Texans owner Bob McNair (No. 879, $1.4 billion), and Tennessee Titans owner Bud Adams (No. 1057, $1.1 billion).

"America's richest practicing lawyer" Joe Jamail Jr., Gulf States Toyota baron Thomas Friedkin, and Houston Astros owner Drayton McLane, who calls Temple home, tied at No. 833, each with $1.5 billion.

All of the Houstonians are relative paupers compared to Mexico tycoon Carlos Slim Helu and family, who topped the list with $74 billion. Microsoft founder Bill Gates is No. 2, with $56 billion and investor Warren Buffet is third, with $50 billion.