Mobile media consumption continues to grow at an astonishing rate, and advertisers are scrambling to catch up. A recent report from eMarketer.com cites huge increases in mobile advertising spend year over year, and projects continued growth in years to come—with global annual revenue expected to reach a milestone of approximately $100 billion by 2018.

As of 2012, mobile ads accounted for only 3% of total spending. But in 2013, global mobile advertising spend more than doubled, and the increase in spending this year is expected to be another 75.1%. The subsequent projected dollar amount for mobile ad revenue in 2014 totals $31.45 billion, vs. less than $9 billion just two years ago.

Why the Sudden Increase In Mobile Advertising?

For the past five years, the consumption share of all other media has been steadily declining to make room for mobile. In that time, TV lost 16% of its total share, Online lost 23%, and Print lost 66%, while mobile was the only venue to see actual growth—and that growth has been more explosive than anyone could have ever predicted. Business Insider reports that mobile media consumption share has risen at an average rate of approximately 50% every year since 2009.

As of 2013, television was the only player to really out-rank mobile in terms of overall consumption, though this stat is somewhat mitigated by the fact that 88% of people report using their mobile device as a second screen while watching tv.

But while mobile consumption continues to grow, proportional ad spend has been slow to catch up. Despite receiving only 3% of total ad revenue in 2012 (already a 119% spending increase over 2011), mobile at that point already accounted for 12% of all media consumed.

In other words, despite the 105% increase in ad spending for 2013, and the projected 75% increase this year, advertisers will still be underrepresenting mobile’s potential reach. Even if mobile media consumption doesn’t grow at all in 2014 (unlikely after 5 years averaging 50% annual growth), it will still boast a 20% share of media consumed, while only accounting for about 10% of total ad spend.

Mobile Marketers Are Catching On

With mobile marketing campaigns showing an ROI dramatically higher than campaigns through traditional channels, the upsurge in mobile spending is clearly not going to stop any time soon. Consumer packaged goods giant Proctor and Gamble recently announced a radically re-concieved marketing strategy that will leverage mobile to create a greater impact on customers, while actually reducing total ad spend.

“We expect marketing spending to come in below prior year levels, due to productivity improvements in non-working marketing and advertising cost,” says Jon Moeller, CFO of Procter and Gamble. “Importantly, the overall effectiveness and the consumer impact over advertising spending will be well ahead of the prior year.”