How to Create a report that shows the amount of leads inserted over a time period and how conversion ratio

How to Create a report that shows the amount of leads inserted over a time period and how conversion ratio

How can I create a report that is going to track on a monthly & yearly basis the amount of leads that are entered and the amount that are converted by lead source and a custom field that I have created (Reason for contacting)?

I'm finding that the leads converted do not show up in the today's leads report that you are able to customize to a certain time period. I am trying to find or create a report that I can have all the information together - the lead source, the reason for contacting, how many leads were inserted over a time period and how many of those leads were then converted and compare.