[perow1]

Forced inspiratory volume corresponds to the volume you can inhale forcefully during the first second of inhalation. This does not neccesarily correspond to the vital capacity.

A value of 7.4lit seems to be a whole lot, since most people cannot fill their lungs completely whitin a second. Are you sure you did not confuse FIV with IV or VC (Inspiratory volume och vital capacity)?

Forced expiratory volume is the amount of air you can forcefully exhale dureing the first second of expiration. This FEV is often expressed in percent. FEV/FVC This gives you a value comparable between individuals of different Vital capacities. A 30 year old male should have a FEV% around at least 80%

The percentage you were given are compared to average values of a person your age and height.

I suspect that you made a measure of your vital capacity and not a forced inspiratory (during one second) measurement and that you also did a FEV test. In that case your FEV% is around 77% which might be about 90% of average. (the numbers do not add up otherwise)