The amount of blood in an adult human is relatively constant: Around 4.7 litres, with of total weight of ~4.4 Kg (average density of blood: ~1.06). Perhaps slightly more (~5 litres?). And slightly less in women. So the percentage of total body weight varies, depending of total body weight. More information and details here: Volume of Blood in a Human
Social issue. A social issue is a problem that influences a considerable number of the individuals within a society. It is often the consequence of factors extending beyond an individual's social issue is the source of a conflicting opinion on the grounds of what is perceived as a morally just personal life or societal order. Social issues are distinguished from economic issues; however, some issues have both social and economic aspects. There are also issues that don't fall into either category, such as warf
The term issue sometimes is used more generally to refer to anything that is a source of conflict or contention, but that is not its meaning here. We are referring to public policy issues, meaning questions of what the government should or should not do. Policy issues involve conflict over the direction of government policy. Some policy issues in an election may be quite specific, such as the conditions under which abortion should be legal.