public static double GetHpLostPercent(this IEnumerable<ShipData> data)
{
var ships = data.Where(s => !s.IsInEvacuationOrTow()).ToArray();
var totalOriginalHp = ships.Sum(s => s.OriginalHP);
var totalNowHp = ships.Sum(s => s.NowHP);
return 1.0 - (double)totalNowHp / totalOriginalHp;
}