There is an effort in the United States is to systematize or put together systems of care that address patients with stroke. And currently there are two recognized levels of organization. The first is a primary stroke center. A primary stroke center is a healthcare facility that is focused on the rapid evaluation and treatment of stroke patients with the focus on using the blood clot dissolving drug tPA. So these are hospitals that resources have been applied to create a team of physicians and other healthcare workers who are in place and are ready 24 hours a day, seven days a week to identify patients with stroke. Rapidly evaluate them and provide them with tPA, if that is appropriate in that case. And really the idea is to try to get as many patients with stroke who come in and who are appropriate and get them treatment as possible. In the past it's been estimated that there's been as few as 2% of stroke patients that actually were able to get this treatment and over the years, we've seen in centers that are organized and do a very good job, that number can be increased into the 15 to 20% range.
