public double GetFreeSlotsPercent(Airline airline, Terminal.TerminalType type)
{
const double numberOfSlots = (22 - 6)*4*7; //from 06.00 to 22.00 each quarter each day (7 days a week)
double usedSlots = AirportHelpers.GetOccupiedSlotTimes(Airport, airline, Weather.Season.AllYear, type).Count;
double percent = ((numberOfSlots - usedSlots)/numberOfSlots)*100;
return percent;
}