Virtually all of the individual donations for the state ballot issue on charter schools has gone toward supporting the measure, according to an online analysis of campaign data sponsored by The Eye and WGBH public radio.

The volume of money flowing to Massachusetts ballot-question campaigns this year is unprecedented, particularly for the charter school question. More than 80 percent of of the $33 million raised by supporters and opponents of Question 2, which would raise the cap on the number of charter schools in the state, comes from organizations.

Charter schools, publicly funded, are operated privately outside traditional school district management. Proponents say they offer wider school choice, and opponents say they are sapping money from traditional public schools. While funding for both sides of the charter question comes primarily from organizations, large individual donations account for more than 40 percent of the fundraising advantage that supporters have available to promote their point of view in advertising.

Families for Excellent Schools Advocacy, Inc., which is based in New York City,  accounts for more than one third of all contributions, having given nearly $13 million in support of Question 2 to date. Supporters have raised more than $20 million in total so far.

Opponents of the charter question, by comparison, have raised $12.5 million, almost all of it from teacher-union groups like National Education Association in Washington, D.C., the Massachusetts Teachers Association, and the American Federation of Teachers, also based in Washington, D.C. But the discrepancy between the two sides is sharpest for individual donors. Where opponents of the charter school question have raised a mere $16,600 from individual contributors, individuals have given $3.6 million in support of the measure.

The largest individual donor to Save Our Public Schools, the committee opposing the charter school question, gave $1,000 to the cause. By comparison, the largest individual supporting donor, Jim Walton, a Walmart heir, has given more than $1 million, and his sister, Alice Walton, also gave $700,000 in favor of the question. Another seven individuals have given $100,000 or more — including former New York Mayor Michael Bloomberg.

Add in another 30 who gave $10,000 or more, plus another 40 who chipped in $1,000 or more to the supporting committees. Only for the smallest contributions under $100 did the question’s opponents raise more than supporters. But such small contributions accounted for just 0.3 percent of contributions from individuals. About a quarter of small donors identified themselves as educators or staff from educational organizations, including public, private, and charter schools, as well as public and private universities.

The campaign finance data for this story was analyzed and prepared by participants at an event hosted by the New England Center for Investigative Reporting and WGBH on Tuesday, Oct. 25. This event was sponsored by a grant from the Institute for Nonprofit News (INN).