Help me fixing task 1 - line graph

The graph below shows the number of enquiries received by the Tourist Information Office in one city over a six-month period in 2011.

The graph indicates the quantity of investigating by the Tourist Information Office from January to June in 2011 in a city. Overall, the number of enquiries in person and by telephone increased significantly while the enquiries by letter/mail decreased. (the letter enquiries)

As the graph is illustrated, there were a significant rise in the number of investigating(queries) by person and by telephone. Especially, the quantity of enquiries in person witnessed a dramatical increase from January to June, made up over 400 in January and then continuing to rise and reach the high at June with around 1900. Similarly, the enquiries by telephone (telephone enquiries) were around 900 in January and decreased slightly to 800 in February. In March, it went up to 1000 and remained unchanged until April and started to rise significantly and accounted for 1600 in June.

By contrast, the number of enquiries by letter/mail experienced a fall in over the period. There was almost 800 for the quantity of investigating by letter/email in January. This number was falling gradually and reached the lowest number in May with nearly 400 and stable it to the end of the period.