Spend is up, click-through rates continue to grow, and mobile is providing a new spin. What must-know channel are we talking about?

Search, of course. Search engine marketing (SEM is a tactic thatmarketers cannot afford to ignore. This week's batch of stats demonstrates why.

1. Eighty-five percent of retailers surveyed said search marketing (including paid and SEO) was the most effective customer acquisition tactic.

2. Seventy percent of agencies predict client SEO budgets would increase this year; 47 percent of respondents said there would be a significant or, at least, some increase to their SEO budget.

3. Nineteen percent of brand marketers expect to significantly increase their paid search investements next year.

4. The average salary for search professionals decreased from $75,543 in 2012 to $68,600 in 2013.

5. Mobile advertising in the U.S. will total $17.73 billion in 2014, withmobile search spending accounting for more than half of that total, or $9.02 billion.

6. By 2018 mobile search spending will reach $28.41 billion, or 85.9 percent, of the U.S. digital search advertising market.

7. The volume of U.S. #google searches about financial topics spikes in the beginning of the year; travel searches are most popular during the summer months; and retail searches start building for the holiday season in September.

8. Google holds a staggering 67.6 percent of the U.S. search engine market share. #bing remains at a distant second with 18.7 percent.

9. Overall search spend in the U.S. grew by 9 percent year-over-year, with most of the increase coming from click growth.

10. When comparing search ad spend in Q2, Google continued to dominate with a 78 percent share of search advertiser spend, while Yahoo/Bing garnered 22 percent of the share. However, compared to Q1 2014, Google search ad spend dropped by 2 percent, while it rose 2 percent for Yahoo/Bing.

11. Much of the growth in paid search can be attributed to increased advertiser focus on mobile devices, including both tablets and smartphones. Spend share on mobile devices continues to climb on a quarter-over-quarter basis, with overall mobile spend share reaching 29 percent.

12. More than 1 billion search queries are made a month on Facebook.

13. Ninety-three percent of online experiences begin with a search engine.

14. Seventy percent of the links search users click on are organic.

15. Search is the No. 1 driver of traffic to content sites, beating social media by more than 300 percent.