Honestly saying the vacancy for any job depends on the requirement of the the particular post for the company or organisation. When it comes to demand of Data Science at the market in present , It is one of the most Demanded Technology . Data Scientist are required all over the globe regardless of how small or big the Company is. Even small to smaller company needs a Data Scientist to analyse the data . Actually we are living in the world of Data and it is must to have someone who has the skills and knowledge to handle all this Data .The skills and knowledge to handle and analyse this Data is acquire from the Course of Data Science.
Hope you can now imagine the demand of Data Science in the market.
For knowing more about why Data Science or a Data Scientist are demanded you can refer to this Quora answer.