In what sequence did the changes take place in Eastern Europe, how did the transformations in some countries cause transformations in?

The changes in Eastern Europe were associated with an acute socio-economic crisis and the overthrow of communist regimes. They took place in the following sequence:
1) Poland – 1988
2) Hungary – 1988
3) Bulgaria – 1989,
4) Czechoslovakia – 1989
5) Germany-1989
6) Romania-1989
7) Albania-1990 8) Lithuania-1990
9) Latvia – 1990
10) Estonia-1990.
11) USSR -1991
There was a chain reaction that resulted in the collapse of the Soviet Union, Yugoslavia, and Czechoslovakia. Some Eastern European countries have joined the European Union and NATO. The political system of the countries of the former socialist community became liberal.