The 1980s were a golden age for the National Security Agency (NSA). Over 90 percent of message traffic was carried by satellites and microwave towers. These were easy to intercept, and the NSA's computers were up to the task of sifting through all the messages looking for useful information. But starting in the 1990s, traffic began to shift to fiber optic cables. Most of the traffic now runs under the ocean via fiber optic cables. These are more difficult to tap into. But that's only a minor problem. The amount of traffic has increased enormously. The internet is largely responsible for this, as is the growing use of cell phones, fax and sending larger amounts of computer data over phone lines. It's much more difficult for the NSA to sort through all the material looking for useful information. Another growing problem is the growth of encryption, which renders the NSAs normal search tools useless. The solution, so far, is to narrow searches; listening in on specific groups at the source of transmission. This is not as effective as the older methods, but the good old days are not likely to return any time soon.