Please review my IELTS essay task I

My essay:
The line graph illustrates the proportion of tourists visiting a Caribbean Island from 2010 to 2017.
Overview, the number of total and visitors staying on cruise ships was a million and 0.5 million respectively.
Visitors who stayed on steamships grew to 0.5 million in 2011 and then declined to 0.25 million in 2012. After that, it increased gradually to 0.5 million in 2013 and grew rapidly to 1 million after a year. During 2014-2016, it experienced a consistent surge to 1.5 million and continued with a sharp rise to 2 million in 2017. In the meantime, the total number increased rapidly throughout the period despite a steady from 2015 to 2016 and reached 3.5 million at the end of the period.
In 2005, the number of tourists staying on the island (0.75 million) experienced a steady until 2011 and rose sharply to 1.5 million in 2013 and then remained stable until 2015. Between 2015 and 2016, it experienced a downward trend to 1.25 million, and it was exceeded by the proportion of visitors staying on cruise ships. Then, there was a growth of 0.25 million in 2017, but the number of tourists staying on the island was the lowest at the end of the period.