The number of oil and gas wells drilled within central provinces of Canada and central U.S. states 1900–2012. Canadian provinces: Alberta, Manitoba, and Saskatchewan. U.S. states: Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah, and Wyoming. (Credit: sciencemag.org) Click to Enlarge.
{"Image Software": "Google", "Image YCbCrSubSampling": "[2, 2]", "Image ExifOffset": "58", "EXIF ExifVersion": "0220", "EXIF ExifImageWidth": "1280", "EXIF ExifImageLength": "544"}