A look at how the electoral map has changed since last August makes two things clear. First, Republicans have gained a very slight additional advantage over the past twelve months. And, second, only one race has been dramatically upended thanks to exciting, titillating revelations.

The Cook Political Report is a well-respected non-partisan handicapping firm that analyzes political races on a regular basis. On Friday, it released its August 1 ratings for contested House races. It released similar data last August 1, giving us a great opportunity to see just how much the national House map changes over time.

As we hinted above, not much. Here's the number of districts that fell into each of Cook's six designations for both Augusts and a mid-way mark, February 6 of this year. The designations range from "Likely" to "Lean" to "Toss-up" for each party, in increasing order of likelihood of a close race.

The increase in February was largely due to there being more Republicans in possibly contested races, likely the result of the fall-out from the government shutdown, after which Cook moved 14 races toward the Democrats.

The two Augusts, though, look pretty similar. This graph still masks a decent amount of information. For example, eight races that were identified as "Likely Republican" got taken out of the rankings, meaning that they're no longer competive at all. But nine races moved in to the rankings, thanks largely to retirements. (More on that below.)

We took all of the contests that appeared on either (or both) lists, and evaluated how much they'd moved toward one party or the other. They're on the map below. Now, please note: A blue district doesn't mean Democrats will win in November, it simply means that a Democratic victory became more likely since last August 1. The darker the color, the greater the movement.

Republicans are likely to pick up two seats thanks to retirements: Rep. Jim Matheson (D) of Utah's 4th announced his retirement in December; Rep. Mike McIntyre (D) of North Carolina's 7th announced his in January.

Democrats aren't locks to pick up any seats thanks to retirements, but several came into play thanks to Republican members calling it quits. Like Rep. Mike Rogers' (R) seat in Michigan's 8th. Had Rogers decided to run for reelection, he would likely have won, according to Cook's 2013 estimate. Now, the seat is listed as leaning toward Republicans, but that's an improvement for the Democrats.

There's really only one race that's been fundamentally transformed by a dramatic turn of events. It's hard to see, unless you zoom in on the New York metropolitan area. Rep. Michael Grimm (R-N.Y.) still represents a district that leans Republican, but investigations into his alleged criminal activity (and a slew of unrelated negative press) helped move his seat to a "Lean Dem" designation by Cook.

Beyond that, most of the races saw no change (the gray districts) from August 1 a year ago. If you give one point for every move between Cook rating categories -- a point to go from Likely Dem to Lean Dem; two points to go from Dem Toss-up to Lean Rep -- you can get a picture for just how much the map has changed. We won't keep you waiting: Republicans have gained seven points on that scale.

Another metric. Last August, 38 races favored Democrats to the Republicans 29 (excluding, of course, all of the races that don't make it onto Cook's spectrum). This August, the spread is 41 to 30. More importantly, eight Democrats and one Republican were in toss-ups last August. This year, it's three Republicans and 13 Democrats.