it varies between the brands but the percentage of alcohol in ber stands at about 5%

The amount of alcohol is dependent on the recipe used. It is also dependent on the jurisdiction in which it is sold, many of which have legal limitations on the maximum amount of alcohol that can be present in a drink called 'beer'. I have drunk beers ranging from about 3% to over 10% alcohol by volume. (At the time, the 10% beer could not be sold in the province next door; there the same brand was brewed to 8%.) Alcohol content has nothing to do with the quality of the product.

How much alcohol IS in beer is generally what it says on the label. This may sound stoopid but is not as straightforward as you would think. In some countries there is no obligation to state the alcohol content while in others it does not need to be stated unless it goes above a certain level. Then again, if you have a beer that continues to mature or ferment in the bottle because it has live yeast in there, the rules vary again. Some countries say you can quote the alcoholic strength at the time of bottling while others (such as most of the US) insist that you quote the highest attainable strength if it continues to ferment right through to the bitter end, so to speak. So a beer that gets legally labelled at 8.2% in Belgium may get labelled 9.2% when it is exported to the US but may typically be 8.5% when consumed, wherever that is. Most countries have the convention of measuring alcoholic strength as the %age of alcohol volume by total volume of liquid (ABV). A few are said to have the system of alcohol by weight (ABW), though I have never seen this in practice. It gives you a lower percentage because the weight of 1 ml of alcohol is less than the weight of 1 ml of water and quite a lot less than the weight of 1ml of water with beer solids in it. A few countries also continue to use the system of degrees proof. These are quoted as the %age of the alcoholic strength that would ignite gunpowder. This is true! A solution of 57.06% alcohol in water ignites standard old-fashioned gunpowder apparently. So 10 degrees proof or 10% proof means a little over 5.7% ABV. How much alcohol CAN BE in beer is a different matter. Standard "wet air" beers than make up most of the stock on a supermarket shelf and the well-known names come in around 3.5-5% ABV. The international range runs from 0% to 27%. Much above 7% ABV you have to bring in special dounble- and triple-fermentation techniques that use different yeast and stronger sugar mixes. Much above 10% you have to employ wine yeast. I doubt more than a dozen of the world's 10,000+ beers are above 13% ABV but there may well be more than 100 that are in the 11%+ bracket.

it can vary quite a bit, any where from 3.2 to i've heard 20%! though most is around 5% or 6%.