2014-06-01 and 2014-06-02 is 1
2014-06-01 and 2014-06-03 is 2
2014-06-01 and 2014-06-04 is 3
2014-06-02 and 2014-06-03 is 1
2014-06-02 and 2014-06-04 is 2
2014-06-03 and 2014-06-04 is 1