The bar graph represents the proportionercentage of people attenting cinemawho go to the movies in particular European countryies throughout the week inover the course of three different years , namely in( 2003, 2005 and, 2007).

"Percentage" sounds more natural here. "Going to the movies" does, too. "In a particular European country" = one country. "In particular European countries" = multiple.

The adverb "namely" means "mostly, above all." You would use it if you describe a category, and then you specify things in the category that you are more focused on. For example:

"Artists from this period use a number of sophisticated techniques, namely chiaroscuro and sgraffito."
"We noticed a few problems with the house, namely some holes in the walls and a broken pipe."
"This product has a number of advantages, namely its two-year guarantee and fast shipping."

When we focus on year 2003, we can observe that on Tuesdays cinemas were attended by twice as many people as on Mondays, then, twice as many people went to the cinema than on Monday. The number remained stable for two days , before reaching a high of two-fifts40% on Saturday and dropping to 30% on Sundays.

The English active voice makes more sense here (I can see why you'd use passive in Russian). I broke the sentence into two parts to make it easier to read. People pretty much always use percentages, not fractions, when talking about graphs.

We can observe the samea similar trend for the year 2005, with some differences.In this year, t6. The perscentage of people was flauctuating ated around 15% from Mondays to Wednesdays, and reached the lowest pointa low of just under 15% people on Thursdays.

"Similar trend" implies that it's the same but a bit different. "Fluctuate," not "flactuate." "Reach a high of" and "reach a low of" are common idiomatic expressions for talking about numbers. They're often used when discussing the weather: "The temperature will reach a high of 70 degrees this weekend before dropping down to the 50s by Monday..."

AtOn the weekend it rai, the number rosed to 45% followed by significantand then dropped to not much more than one thirdabout 30%.

As the year 2007 is conserdDuring 2007, the lowest percentage of people werewas recorded on Wednesdays( (just under 10%), followed by generalan increase for the subsequent days, despitethen a slight drop to approximately 30% on Sundays.

It's clear from the context that the number you're talking about is the percentage of people, so you can just say "percentage." Because percentage is a singular noun, you write "was recorded," not "were recorded." "Then" makes more sense than "despite" because you're talking about a sequence.

In sumOverall, Saturdays were the most popular for attending cinemas induring those three years, whereas Mondays and Wednesdays were the least popular over the same period of time.

I cut the last part of the sentence because it's already implied by the context.