Question: How much of the US national debt is owned by the country of the philosopher who accurately described evaporation?

<P0-S0> Wang Chong (; 27 – c. 100 AD), courtesy name Zhongren (仲任), was a Chinese meteorologist, astronomer, and philosopher active during the Han Dynasty. <P0-S1> He developed a rational, secular, naturalistic and mechanistic account of the world and of human beings and gave a materialistic explanation of the origin of the universe. <P0-S2> His main work was the "Lunheng" (論衡, "Critical Essays"). <P0-S3> This book contained many theories involving early sciences of astronomy and meteorology, and Wang Chong was even the first in Chinese history to mention the use of the square-pallet chain pump, which became common in irrigation and public works in China thereafter. <P0-S4> Wang also accurately described the process of the water cycle. <SEP> <P1-S0> the european central bank had stepped up the buying of member nations debt. <P1-S1> in response to the crisis of 2010, some proposals have surfaced for a collective european bond issue that would allow the central bank to purchase a european version of us treasury bills. <P1-S2> to make european sovereign debt assets more similar to a us treasury, a collective guarantee of the member states' solvency would be necessary. <P1-S3> [b] but the german government has resisted this proposal, and other analyses indicate that "the sickness of the euro" is due to the linkage between sovereign debt and failing national banking systems. <P1-S4> if the european central bank were to deal directly with failing banking systems sovereign debt would not look as leveraged relative to national income in the financially weaker member states. <SEP> <P2-S0> As of April 30, 2018, debt held by the public was $15.3 trillion and intragovernmental holdings were $5.7 trillion, for a total or ``National Debt ''of $21 trillion. <P2-S1> Debt held by the public was approximately 77% of GDP in 2017, ranked 43rd highest out of 207 countries. <P2-S2> The Congressional Budget Office forecast in April 2018 that the ratio will rise to nearly 100% by 2028, perhaps higher if current policies are extended beyond their scheduled expiration date. <P2-S3> As of December 2017, $6.3 trillion or approximately 45% of the debt held by the public was owned by foreign investors, the largest being China (about $1.18 trillion) then Japan (about $1.06 trillion). <SEP> <P3-S0> there is also a widespread view[vague][who?] <P3-S1> that giving much more financial support to continuously cover the debt crisis or allow even higher budget deficits or debt levels would discourage the crisis states to implement necessary reforms to regain their competitiveness. <P3-S2> [citation needed] there has also been a reluctance[citation needed] of financially stable eurozone states like germany[citation needed] to further circumvent the no-bailout clause in the eu contracts and to generally take on the burden of financing or guaranteeing the debts of financially unstable or defaulting eurozone countries. <P3-S3> [citation needed] <SEP> <P4-S0> Han-era astronomers adopted a geocentric model of the universe, theorizing that it was shaped like a sphere surrounding the earth in the center. <P4-S1> They assumed that the Sun, Moon, and planets were spherical and not disc-shaped. <P4-S2> They also thought that the illumination of the Moon and planets was caused by sunlight, that lunar eclipses occurred when the Earth obstructed sunlight falling onto the Moon, and that a solar eclipse occurred when the Moon obstructed sunlight from reaching the Earth. <P4-S3> Although others disagreed with his model, Wang Chong accurately described the water cycle of the evaporation of water into clouds.