IELTS writing task 1 while sentences

IELTS Writing Task 1: 'while' sentences
In writing task 1, you usually need to make comparisons. A good way to do this is to
write a complex sentence using the word 'while'. I wrote two such sentences in
my essay last week. Look carefully at where I put the comma in each sentence.
1) 'while' at the beginning of the sentence:
While the numbers of people who use the car and train increase gradually, the number of
bus users falls steadily.
2) 'while' in the middle of the sentence:
In 1970, around 5 million UK commuters travelled by car on a daily basis, while the bus
and train were used by about 4 million and 2 million people respectively.