How have the traditonal roles of man and woman changed in the last century?

In which country or area?
I believe that would make a significant variance in the answer.
The whole world is changing but in some places its considerably more rapid than others.

Going to a sociology book would give you great insight into your question. Generally speaking, the male (in the early 20th century) was the head of the household, the breadwinner, the patriach that held and carried the reponsibilities of his family. While some women worked outside the home, it was not the common practice for a woman to do so. She was the at home mom, the homemaker, the stay at home housewife, who did all the other work ( housework, child rearing, cooking, laundry, etc.). Often the wife did not have any of the financial details even of the household. That was all left to the husband.

Economic patterns caused by a variety of reasons led the woman to seek outside employment in order to help the family survive. When you look at the Depression era, everyone who could find a job, took it and added to the family income. That means children too. WWI and WWII had a huge imapct on women in the workforce - especially WWII. Men were off to war and women went to the factories. Women had to be the breadwinner, the Mom and the overseas Dad to the family.

The shift in society did not change in one decade alone, it was growing from the 1920's when you saw women defying social mores and becoming independent. Women have had to adapt to their family situation, such as a divorce when they were placed into a role that some were not prepared for at all.

Each decade can point to an event or series of events that lend to the crisscrossing of roles in a relationship. The broadening of both roles. It is harder to find the old "traditional marriage" now with both spouses working, juggling family and responsibilities. People have to adapt. For example, look at the number of men that cook and can prepare the dinner. You would not have seen that (or else had to look hard to find it) 100 years ago. The partnership is more on an equal basis.

I hoped that has helped you, even a little bit.

Thank you very much :)

In which country or area?
I believe that would make a significant variance in the answer.
The whole world is changing but in some places its considerably more rapid than others.

Especially in Europe.