Four in five non-candidate ad dollars have gone to attack spots in the general election. Here’s how that money’s been spent

This post has been updated.

Political television ads have been overwhelmingly negative this year thanks to a record amount of independent spending that has overwhelmed the messages of candidates in many competitive races.

More than 80 percent of the money spent by big-money independent groups and parties in the general election has gone to ads that oppose a candidate, according to a Washington Post analysis of campaign finance data published Wednesday.

A leading ad tracking firm has tracked top attack ad trends. Here's what they found:

Amid the negativity and all the attention paid to concerns about Ebola in recent weeks, only three campaign ads have mentioned the deadly virus.

Ads mentioning the virus haven't aired much in recent weeks -- and until this week, they had both been produced by Democrats, even though Republicans are the ones raising concerns about the spread of the virus and criticizing the Obama administration and Democrats for a bungled response to the health crisis.

That changed with a campaign message from Rep. Steve King (R-Iowa) that referenced the virus visually. That spot began airing Tuesday:

Michelle Nunn, the Democratic Senate candidate in Georgia, aired this ad in early October in the military-heavy markets of Columbus, Macon, Savannah and Augusta. It went after her GOP opponent, David Perdue, on the issue of military spending:

The first of the ads mentioning Ebola aired in late August, when Sen. Mark Pryor (D-Ark.) ran this ad that blasted his opponent, Rep. Tom Cotton (R-Ark.), for voting against federal pandemic response funding:

"Despite all the talk about it, we have not captured any other ads that mention Ebola," said Elizabeth Wilner, senior vice president of Kantar Media Ad Intelligence who oversees its Campaign Media Analysis Group and tracks ad messaging in a regular column for The Cook Political Report.

CMAG has been tracking and issue-coding ads in the Senate races nationwide -- and in the closing weeks, health-care related messages remain dominant. This ad released Tuesday by Cotton is just the latest example of a Republican trying to tie a Democratic opponent to the Affordable Care Act. The message stars an elderly couple concerned that their Medicare benefits were slashed because of that law, with Pryor's support:

In an interview, Willis said that the frequency of ads attacking the health-care law registers so high in their tracking in part because candidates for lower-tier state races keeping raising the issue, even if it isn't directly tied to the position they're seeking. For example, Alabama Republican Attorney General candidate Luther Strange is airing this ad that calls his Democratic opponent, Joe Hubbard, "an Obama liberal" in part because he supports the health-care law:

(In response, a Hubbard campaign aide said via e-mail that the Strange ad makes "false misleading claims. In fact, Joe Hubbard did not support the President's health care plan.")

Ads that mention job creation or job losses remain the second-most mentioned issue, according to CMAG. The popularity of the issue is shows up again in Georgia, where Nunn has been airing this ad against Perdue to raise questions about his decision as a business executive to outsource some business services and jobs:

Perdue has been forced to respond to the ad in this direct-to-camera appeal that also knocks Nunn's associations with President Obama:

The third-most popular issue, according to CMAG's tracking, is taxes -- thanks mostly to Democratic-sponsored ads that attack Republicans for allegedly supporting tax breaks for wealthy Americans or corporations.

This recent message by the Senate Majority PAC, airing in Kentucky against Senate Minority Leader Mitch McConnell (R-Ky.), is a prime example of the genre:

In a notable jump up the list, the fourth most-popular subject in ads is energy and the environment. Republicans have been running more ads that mention the, mostly to highlight concerns with the delayed approval of the Keystone XL pipeline. Here's a great example of an energy-themed ad from Rep. Cory Gardner (R-Colo.), who's hoping to unseat Sen. Mark Udall (D-Colo.):

But tracking suggests that stepped-up advertising by environmental rights groups -- including this message airing in Iowa attacking GOP Senate candidate Joni Ernst from the NextGen Climate Super PAC -- is part of what's pushing energy and environmental ads further up the charts:

Ads related to budget or spending concerns have dropped in the past week to the seventh most-frequently mentioned issue, down from third. But this message released Tuesday by Democrat Alison Lundergan Grimes in her race against McConnell seeks to make an issue of his allegedly lackluster support for transportation funding:

Ads that mention Social Security also jumped to the 10-most mentioned issue list, up from 14th the week before, according to CMAG's tracking. Several super PACs are raising the issue on behalf of Democrats, but here's a new ad on that front from Rep. Bruce Braley (D-Iowa), who's running against Ernst in Iowa:

The airwaves may be flooded with negativity, but there's good news on the horizon for voters: Election Day -- and relief from the attack ad deluge -- is less than two weeks away.