How to group duplicate date rows into new columns

Question

I have an issue that relates to the following example. Given a dataframe which looks like this

           Country Population
Date                  
2016-01-01  A       10
2016-01-01  B       100
2016-01-01  C       1000
2016-01-01  D       10000
2017-01-01  A       20
2017-01-01  B       200
2017-01-01  C       2000
2017-01-01  D       20000
2018-01-01  A       30
2018-01-01  B       300
2018-01-01  C       3000
2018-01-01  D       30000

I wish to have the output looking like this

            A       B       C       D
2016-01-01  10      100     1000    10000
2017-01-01  20      200     2000    20000
2018-01-01  30      200     3000    30000

The problem is I have a very large dataset (22.000+ rows) with the string column (Country) being of many different strings, where I may not know all of the different strings.

I've tried working around with the function .groupby() but unsuccessful. Any ideas how to get the result?