The battle of the search engines is raging, and Yahoo is currently enjoying the highest share numbers it has seen in the past five years. This gain has been largely attributed to Firefox’s replacement of Google with Yahoo as its default search browser. Meanwhile, Google just reported their lowest United States search share numbers ever recorded by the company.

Yes, Google’s share numbers are dropping, but this was pretty much inevitable at some point. In a market they have so thoroughly dominated, Google had nowhere to go but down. Perhaps the only surprise is how quickly the numbers are shifting. (In a previous blog highlighting SEO trends in 2015, we recommended that sites should begin to optimize for other search engines. Were you listening?)

According to StatCounter, a trusted SEO statistical source, the most popular search engine fell below 75% in the US for the first time since June 2008. Bing is still the second most popular search engine, but Yahoo isn’t far behind.

In a report on US search engine usage specifically by Firefox users, Yahoo-on-FIrefox usage increased from 9.9% in November 2014 to 28.3% in January 2015. Google-on-Firefox usage fell from 81.9% to 63.9%. When eliminating Firefox from the search data, Yahoo’s gains and Google’s losses were eliminated. As the year goes on, Yahoo may also be picked up by Safari, which will make the search engine’s numbers climb even faster.

While Google is still dominating the market, Bing and Yahoo shouldn’t – can’t – be ignored. If your content isn’t optimized for each search engine, a significant loss of traffic could result.