Reading Section Part C : Question 1

Human beings have been communicating with one another for thousands of years. Without communication, civilization as we know it would not exist.
It is amazing to think that, when communicating with other humans who were far away, few methods of communication were available until the discovery of electricity. Subsequent inventions, such as the telephone in the 19th century, provided additional ways to convey messages in interpersonal relationships. As a result, sending handwritten letters, which had been the prominent way to communicate, slowly began to lose its dominance.
Nowadays, with the popularity of email, many people feel that the traditional post office will soon belong to a distant age. In 1995, statistics in Japan showed that on average, almost 200 letters and parcels were sent per person per year (this figure included commercial mail sent by businesses). However, the situation has changed dramatically since then.
But even after email became popular in the late 20th century, postal mail was still preferred by many people because they felt that it gave a polite and sincere impression to the recipients. According to a contemporary report, almost 50% of people thought that communicating through handwritten letters was more polite. Furthermore, more than 40% believed that they could feel the sincerity of the sender when receiving a letter. However, the main reason for choosing letters as a tool of person-to-person communication was that letters expressed a person's feelings better than email did, which was confirmed by about 56% of the people in the survey. Nevertheless, the convenience and low cost of email caused it to be used far more frequently than handwritten letters.
In spite of the prevalence today of the telephone and email, postal mail is still an important means of communication for those who want to convey their messages sincerely.

What caused the sending of handwritten letters to begin to become less popular?