It varies depending on where in the body you measure. It's also function of your heart rate. A heart will pump up to about half a cup per beat, and that will be replaced by the next heartbeat. To transfer that volume to speed, we need to think about the size of the vessel- the aorta is large, so that half a cup doesn't have to move far to make room for the next lot in the next heartbeat. However, counter intuitively, this doesn't mean it moves faster in the smaller vessels. Because there is a greater total cross sectional area across all of the small vessels, it slows down. The water in the big hose moves quick, to supply lots and lots of small hoses which move slow. Searching around tells me it ranges from a fast walking speed in the aorta, to something like the second hand on a watch in some capillaries with a low oxygen requirement.