Please review my IELTS essay

My topic: The chart below shows the total number of minutes (in billions) of telephone calls in the UK, divided into three categories, from 1995-2002. Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

My essay:

The bar chart displays the total amount of time spent on telephone calls in the UK in three different types over the period from 1999 to 2002.

Overall, the local fixed line which remained the most favored kind of telephone calls in UK, showed the decrease in the three years. While the total minutes spent on national, international and mobiles calls increased significantly from the beginning to the end of the surveyed time.

Looking at the detail, the British consumed over 70 billions minutes for local calls, which reached the peak of 90 billions in 1999. From 1999 onwards, the local categories showed the downward trend and went for again 70 billions minutes in 2002, but still was the most popular way of making calls in UK.

In contrast, the number of calls through national and international line gradually rose during the period shown, from over 36 billions minutes in 1995 to over 60 billions in 2002. Furthermore, the number of minutes consumed via mobiles accounted for the lowest part in 1995, at around 3 billions. This category of UK telephone calls then considerably climbed up through a period of 7 years and peaked 45 billions minutes in the last year.