What were the 20 most significant events of the 20th century?

Hello, I'm a young student and for a school work, I need to make a paper of 20 lines. Each line is a year from 1900 to 1999 and I need to write the most significant event that has occurred during each year. For example, 1945: death of Hitler. I have searched and written some events but I still have 15 years to fill. I can't do it alone. Someone can help me?