Article: At her Silver Jubilee in 1977, the crowds and celebrations were genuinely enthusiastic, but in the 1980s, public criticism of the royal family increased, as the personal and working lives of Elizabeth's children came under media scrutiny. Elizabeth's popularity sank to a low point in the 1990s. Under pressure from public opinion, she began to pay income tax for the first time, and Buckingham Palace was opened to the public. Discontent with the monarchy reached its peak on the death of Diana, Princess of Wales, though Elizabeth's personal popularity and support for the monarchy rebounded after her live television broadcast to the world five days after Diana's death.

Question: When was Elizabeth's Silver Jubilee?
1977