You can write a graduation thesis on the declining turnover of enterprises year by year, which is a very practical and challenging topic. In the paper, you can discuss the reasons, influencing factors and countermeasures that enterprises can take. The following are some possible research directions and viewpoints:

1. Market changes: The decrease in turnover may be caused by changes in market demand or consumption habits. You can deeply study market trends and consumer behavior, and analyze the factors that lead to the decline in turnover.

2. Competition analysis: The decline of enterprise turnover may be related to the increase or enhancement of competitors. You can investigate your competitors and discuss their advantages and strategies, so as to provide countermeasures for enterprises.

3. Market positioning: The decline of enterprise turnover may be caused by market positioning problems. You can analyze the enterprise's market positioning strategy and target audience, evaluate its effectiveness, and put forward suggestions for improvement.

4. Marketing: The decline in turnover may be related to the inadequate or unreasonable marketing activities of enterprises. You can evaluate the marketing strategy of the enterprise and propose improvement measures to attract more customers and increase sales.

Please note that the above are just some examples of research directions, and you can make further choices and explorations according to the specific situation and feasibility. When writing a paper, you must quote appropriate theories and data in the paper for full analysis and explanation. Remember to quote and write references accurately according to the requirements of papers and academic norms. Good luck with your writing!