Please evaluate my ielts writing task 1

The graph below shows the number of passenger railway journeys made in Great Britain from 1950 to 2004.

Starting from one billion in 1950, the national rail network peaked at 1.1 billion in 1960. And then, there was a downward trend in the next 20 years until 1980. It reached its minimum at 600 million this year. Comparatively, the number of London underground in the 1950s was only 2/3 of the national rail network, which is about 750 million. This figure remained stable for the next score. Followed by a gradual decline to the lowest level at 0.5 billion around the mid-1980s. Thereafter, both of them had a very similar pattern as they showed a 20 years surge towards 1 billion passengers until 2004/05.

On the other hand, the light railway and metro system have a lower figure in passenger railways——under 10 million from 1965 until the 80s. Nonetheless, since 1980, the following 2 decades saw a slight increase and finally reached it's maximum at 200 million in 2004/05.

To sum up, both London underground and national railway network carries the most passengers while the light rail and metro system carries the least.