The graph below shows the consumption of fish and some different kinds of meat in a European country

chicken, beef, lamb and fish consumed in Europe

The line graph illustrated the amount of fish and three kinds of meat, namely: chicken, beef and lamb consumed by a European country over the course of 25 years starting in 1979.

Looking at the graph, it is immediately obvious that the amount of chicken consumption experienced an upward trend while the overall figures decreased. Throughout the period, the consumption of chicken registered the highest figure out of 4 products studied.

In 1979, the amount of chicken eaten by a person every week stood at approximately 140 grams before rocketing at around 250 grams at the end of the period. An opposite pattern was seen in the fish consumption, which experienced a slightly decline from about 65 grams to below 40 grams in 2004.

At the beginning of the period, the consumption of beef was about 220 grams each person a week, this figures also showed a significant decrease to nearly 120 grams between 1984 and 2004 after sharply fluctuating before 1984.There was a similar development in the amount of lamb consumed, which gradually fell from 150 grams to 70 grams per person per week.

If you could provide the graph that you are referring to, it would help with providing more substantial feedback on your essay.
Speaking of writing technicalities, I would suggest revising a few of your lines to ensure that the delivery of your message is clear.
For instance, I could revise your first paragraph/sentence as:
This line graph illustrates the amount of fish and meat consumed by a European country over 25 years beginning from 1979. The meat types included here are: chicken, beef, and lamb.

Please take note of three things I have done here:
Ensured that I used present tense because I am describing a graph that is present in front of the reader. This makes the text appear more interactive - and is the formal way of approaching language.

I used "from 1979" instead of "in 1979" because you're referring to a point in time onwards rather than a single point. Please review prepositions' usage regarding this.

I created more clarity in the structure by not confusing readers with introducing the three meat types before finishing the initial thought of the message.

Keep in mind these points and apply the entirety of your essay.
I would suggest revising your last paragraph. There were instances wherein you were dragging the sentences, creating run-on phrases instead of articulating clearly what you want to relay. Moreover, using technical terms such as "base year" can help your essay be more academically and professionally proficient.

For instance, I would revise your first line here as:
The beginning of the period had a weekly consumption of 220 grams of beef per person. This fluctuated into a significant decrease of consumption between 1984 and 2004, following a fluctuation prior to the base year.

Best of luck to your essay.