GIven data like design an efficient DS for below operations.

{"eventName":"event1","date":"date1"},
{"eventName":"event2","date":"date2"},
{"eventName":"event3","date":"date3"},
{"eventName":"event4","date":"date4"},
{"eventName":"event5","date":"date5"},
{"eventName":"event6","date":"date6"}
We have below 3 operations

1. given a date , find number of events happened on that day
2. given two dates , find the number of events happened in that duration
3. given a eventName and date , find if the event happened on that date