If a person had 70-90 breathes in one minute, they wouldn't be human anymore. The average adult breathes in and out every 4-5 seconds or so. If you are an adult and your respiration are between 12 and 25, then you need not worry. Outside of that (when your body is at rest), then you should be worried.

The normal range of breaths per minute for an adult (relaxed) is between 9 and 14, one breath meaning one movement of the chest, up and down. This will obviously increase upon exercise. If your respiration rate is above, this could indicate that you are not getting enough oxygen into your lungs and around your system. People who suffer from asthma or breathing, heart or respiratory problems tend to have higher respiration rates. Some medications especially pain medications can lower your respiration rate also .

Normal breathing rates fall between 12-20 per minute. Either above or below this range will result in inadequate profusion.

You begin to breath faster when exercising because your muscles are using more oxygen than when you are resting and so you breathing increases in order to supply your muscles with enough oxygen.
The more you exersice the more useage of oxygen in the blood. So the blood has to travel faster in order to keep up with the high oxygen demands. Therefore the heart pumps faster, to allow for faster diffusion rates of O2, during exercise.
this is because the more excersize you do, the more oxygen is needed in the mitochondria of your muscles to convert glucose into energy. therefore the more you breathe, the higher intake of oxygen is obtained, thus providing reactants for aerobic respiration to continue before anaerobic respiration takes over.
because our muscles need more oxygen in order to carry out respiration and burn energy. When you breathe, you inhale oxygen into the air sacks in your lungs called alveoli. Then it is transferred to your bloodstream on red blood cells by a pigment called hemoglobin The oxygen goes into your blood by a gas exchange called diffusion. This is when oxygen goes into your blood and carbon dioxide comes out because too much is harmful to your body. These will then carry it to your cells in the muscle where energy is burned and respiration occurs. Therefore, you will need to take more breaths to keep getting more oxygen into your body.
When exercising, most of the muscles in our body speed up their metabolism. As they run out of energy, the body needs to produce more energy. More oxygen is required to produce the energy needed to keep exercising and other processes.

In a way, the increased need for energy causes our body to "starve" for oxygen. The instinctive response we have to compensate for this sudden need of oxygen is breathing faster.

When you exercise you have an increase in the depth of breathing. Your muscles need more oxygen during exercise because they need to produce more energy to work for long periods of time and they do this by breaking down glucose in your food but they need oxygen to do this. Without an increase in oxygen the muscles will try to produce energy through the anaerobic energy system to make ATP but this creates lactic acid. Before you begin exercising you get a small rise in breathing rate and this is called anticipatory rise. When you begin exercising there is a noticeable increase in breathing rate and after a few minutes of aerobic exercise your breathing continuous to increase but eventually levels off if the intensity remains constant. If you are exercising at your highest possible intensity then your breathing rate will keep increasing until exhaustion. After exercise the breathing rate returns to normal rapidly to begin with and then more slowly.
an increase in breathing rate is brought about as exsersize because when you exersize your heart beats faster and it means that your blood stream needs more oxygen which means you have to breath more a second.
Well, when you exercise you use more oxygen, there fore you need to get more oxygen into your body and you breathe fast and that raises your breathing rate. When you finish exercising you need to get more oxygen into your body, before it goes back to normal. It slowly gets back to normal after you finish exercising.
Breathing is all to do with getting more Oxygen into the body and out. During exercise, the muscles need more energy, and so the blood needs to move faster around the body, causing the lungs to work harder and causes the heart to beat faster, to get more blood around quicker. To get more energy, more air must enter the lungs, and so faster breathing. Hope this helps :D

This one is simple, just watch the patients chest for breathing movements for one min. (or 30sec x 2, or 15sec x 4 ect...) The result should be amount of breaths per minute. A normal individual will breath at rest about 12-16 per minute.