Handling NA Values in the Chicago Crime Rate data set
Assuming Im reading the format of you table correctly, the NA's are exclusively for geo-location attributes. With "District" being the most complete field with only 47 missing values. Are the locations of certain crimes censored for data privacy reasons?

Of the 6 M crimes in your data set:


10 % or ~600,000 are missing or censored for Ward, Community area or name
1 % or ~60,000 are missing spatial coordinates.


You could determine most of the missing Ward and Community data by analysing the coordinate pairs in a GIS.

How you handle missing data will largely be determined by the hypothesis and analysis you intend to do. You mention Time Series, it should be fine to include all crimes for straight time series at the Chicago level. For higher spatial resolutions, you can do district (dropping 47 Missing points), and so on. How much effort you devote to handling the missing data, such as by using steps outlined above, will depend on how useful that data may be for your analysis. I suspect that most people working with this data tend to drop the NA's as they are mapping the crime rates in different areas.