Percentage of Benjamin Netanyahu’s 2014 primary-campaign contributions that came from the United States : 90

That came from three U.S. families : 30

Year in which the first female U.S. senator took office : 1922

In which a female senator first used the Senate swimming pool : 2008

Average rating for promptness in returning student work, out of 5, received by an online-course instructor believed to be male : 4.4

By an instructor who returns student work at the same time and is believed to be female : 3.5

Percentage of U.S. children in 1960 who lived in households headed by heterosexuals in their first marriage : 73

Who do today : 46

Percentage of married U.S. households that are multiracial : 7

Of unmarried U.S. households : 14

Number of the ten states with the highest turnout of black voters in 2008 that subsequently passed voter-I.D. laws : 6

Percentage of African Americans who said in 2012 that gun ownership protects more people than it endangers : 29

Who say so today : 54

Percentage change since 2000 in the number of Mexicans apprehended at the U.S.-Mexico border : –86

In the number of non-Mexicans : +783

Estimated number of traffic enforcers who wore diapers during the pope’s January visit to Manila : 2,000

Portion of Chinese trade that is not conducted in Chinese currency : 4/5

Number of U.S. congressional districts in which trade with China has produced more jobs than it has cost : 1

Hours per day that a death-row inmate in China wears hand and ankle restraints : 24

Minimum number of people hospitalized in Tokyo after choking on mochi rice cakes during New Year’s celebrations : 18

Chance that a high-risk patient admitted to a U.S. teaching hospital for heart failure will die : 1 in 4

That one admitted during a national cardiology conference will : 1 in 6

Percentage of H.I.V.-positive Americans who are not receiving regular treatment : 66

Ratio of annual opioid-painkiller prescriptions in Alabama to people in the state : 1.43:1

Estimated minimum gallons of water used annually to produce Coca-Cola products : 8,000,000,000,000

Portion of the world’s population that amount could supply with drinking water each year : 1/4

Portion of Americans who say they would ride in driverless cars if the technology were available : 1/2

Who say they would get memory chips installed in their brains : 1/4

Total number of passenger planes that have gone missing without a trace since 2000 : 10

Estimated minimum annual cost of fraudulent salaries paid to Iraqi “ghost soldiers” : $380,000,000

Percentage change since 2009 in the annual number of military-grade weapons purchased by the United States : –5

By France : +9

By Russia : +20

Respective rank of Great Britain and France among world leaders in G.D.P. in 2012 : 5,4

Respective rank in 2013, after Great Britain began accounting for prostitution and illegal drugs : 4,5

Ratio of money spent by Britons on prostitution to that spent on hairdressing : 1:1

Percentage change since 1993 in the annual sales of vinyl records in the United States : +2,590

Date on which the first recreational-marijuana store opened in Colorado : 1/1/14

Percentage change since that time in out-of-state undergraduate applications to the University of Colorado Boulder : +39

Figures cited are the latest available as of January 2015.

“Harper’s Index” is a registered trademark.

March Index Sources

1,2 Office of the State Comptroller of Israel (Jerusalem)

3 U.S. Senate Historical Office

4 Architect of the Capitol (Washington)

5,6 Lillian MacNell (Raleigh, N.C.)

7,8 Pew Research Center (Washington)

9,10 U.S. Census Bureau (Suitland, Md.)

11 Brennan Center for Justice (N.Y.C.)

12,13 Pew Research Center (Washington)

14,15 U.S. Customs and Border Protection (Washington)

16 Metropolitan Manila Development Authority (Manila, Philippines)

17 HSBC (Hong Kong)

18 Economic Policy Institute (Washington)

19 Human Rights Watch (Hong Kong)

20 Tokyo Fire Department

21,22 Anupam Jena, Harvard Medical School (Boston)

23,24 Centers for Disease Control and Prevention (Atlanta)

25,26 Bartow J. Elmore, University of Alabama (Tuscaloosa)

27,28 Pew Research Center (Washington)

29 Aviation Safety Network (Roosendaal, Netherlands)

30 Embassy of the Republic of Iraq (Washington)

31–33 Stockholm International Peace Research Institute (Solna, Sweden)

34,35 Centre for Economics and Business Research (London)

36 Office for National Statistics (London)

37 Nielsen (Los Angeles)

38 Office of the Governor of Colorado (Denver)

39 University of Colorado Boulder.