The defense company has increased its dividend for the last 21 years.Investors often choose U.S. defense stocks because they are attached to relatively safe companies. The U.S. government is a reliable customer, and there's no shortage of geopolitical tensions driving increased demand for defense spending around the globe. Moreover, stocks like Lockheed Martin (LMT -0.01%) tend to pay growing dividends.The chart below shows the stock's dividend-per-share, earnings-per-share, and free-cash-flow-per-share rat ...