Ever wish that there was one place with all of the need-to-know mobile statistics?

Mobile Marketer has compiled a list of the most useful stats looking back on 2011. Sources include Mobile Future, eMarketer, Return Path, Yahoo and Scanbuy. 

- 1 billion app downloads

- $3 billion paid by Apple to independent app developers

- 166 percent increase in Facebook Mobile users in the first half of 2011

- 103 million wireless tweets were posted each day

- 1 billion foursquare check-ins

- 8 trillion tests sent, up 1.1 trillion from last year

- 1,800 percent increase in traffic on networks in the United States in next four years

- More smartphones bought in the U.S. than PCs

- More wireless subscriptions in the U.S. than people

- 2 billion networked devices by 2015

- Six carriers rolled out 4G services in 2011

- 2.4 million American jobs supported by wireless 

- $27.5 billion investment in U.S. mobile networks by wireless carriers 

- 500,000 jobs and $400 billion to U.S. GDP with additional 500 MHz of additional spectrum 

- Mobile commerce sales will reach $6.7 billion this year in the U.S. ? a tiny fraction of overall retail sales, to be sure, but a 91.4 percent increase over 2010 

- Next year, sales will rise another 73.1 percent to $11.6 billion

- Mobile advertising will generate $1.23 billion in the United States in 2011

- Mobile advertising in the U.S. to reach $4.4 billion by 2015

- Mobile email open rates increased 34 percent in the past six months

- In particular, email opens from iPad devices skyrocketed by increasing 73 percent

- 20 million bar code scans in third quarter 2011

- 40 percent increase in scans year-over-year from the third quarter of 2010

- Consumers are spending 29 percent more time watching videos on their mobile devices

- 77 percent of tablet owners use their devices everyday 

- 53 percent of users depend on tablets for daily news